Revision work for Leaving Certs 2014/2015.

 
 
 
 

Use These to study experiment questions 

 
 
 
 

Section 1. Questions covering Electricity, Resistance, Semiconductors & Heat

 

Q1. What are the three effects of an electric current and how would you show each?

Q2. If 2amps of current is flowing in a circuit for sufficient time to allow 12C of charge to pass. How long will the current have been flowing?

Q3. Why is it ok to connect an ammeter in series in a circuit?

Q4. What is the difference between potential difference and electromotive force?

Q5. If three 12v batteries are connected in series what will the output voltage be? What would the output voltage be if the batteries were connected in parallel?

Q6. Derive the formula for resistances connected in series.

Q7. If a 5, 10, and 15 ohm resistor were placed in series, what would the overall resistance of the resistors be? What would the overall resistance be if these resistors were set up in a parallel configuration?

Q8. A current of 8amps flows through a circuit. It reaches a junction in which there are two resistors in parallel. One of the resistors is a 2 ohm resistor and the other is a 3 ohm resistor. How much current will flow in the 3 ohm resistor?
Q9. Find the resistivity of a wire with a diameter of 2mm and a length of 1.2m who's resistance is 10 ohms.

Q10. Resistor one in a Wheatstone bridge is 10 ohms resistor two is 20 ohms, resistor four is 60 ohms. Find the resistance of the third resistor.

Q11. 3kg of water is in a kettle at 15 degrees Celsius. The kettle takes 9 amps of current when it is plugged into the mains power supply of 240v. What is the power rating of the kettle? Given that the specific heat capacity of water is 4200j/kg/k how long will it take to boil the water?

Q12. Sketch the graph of current against voltage for: a semiconductor, a filament bulb.

Q13. Explain with the aid of a diagram how you would wire a standard three pronged plug.

Q14. What is doping when dealing with semi conductors give examples

Q15. How is a depletion layer made in a semiconductor

 

Section two Chapters on waves static capacitance etc!


 

Q1. What type of wave is a sound wave. Name some features of this type of wave.
Q2. Define the following: overtones, loudness, resonance, threshold of hearing, sound intensity at a point, and fundamental frequency for an object.
Q3. If a wire is 2m long and has a mass of 0.25kg and is under tension of 150N. Calculate the fundamental frequency of vibration.
Q4. Define the following: diffraction grating, polarisation, dispersion, electromagnetic spectrum.
Q5. A diffraction grating has 550 lines per mm and the angle between the second order fringe to the right and the second order fringe to the left is 100 degrees. Find the wavelength of the light.
Q6. Define the following: conductor coulombs law, electric field.
Q7. Describe how you would charge an object using (just one) by induction. Use diagrams to aid your explanation.
Q8. Two charges of charge 10C are placed a distance of 3m apart. The permittivity of free space is 8.9x10-12 fm-1. The charges are in an environment which has a relative permittivity of 5. Find the force of attraction between the two charges.
Q9. A charge of 5 micro coulombs experiences a force of 50N when in an electric field. Find the electric field strength.
Q10. Find the electric field strength at a distance of 2m on a charge of size 3 micro coulombs in a material with permittivity of that of air which is 8.9x10-12fm-1.

Q11. How would you use a gold leaf electroscope to test whether a charged rod is positively or negatively charged?

Q12. Coulombs law is an inverse square law. What does this term mean?

Q13. Define the following: Potential difference, Capacitance, the Farad.

Q14. Find the work done in bringing a charge of 3 Coulombs through a potential difference of 6 volts.

Q15. The capacitance of a Van de Graff generator is 3x10-11F and it usually reaches a voltage of 250 KV. Find the typical charge that would be present on the dome.

Q16. What are the factors that affect the capacitance of a parallel plate capacitor?

Q17. Find the relative permittivity of a medium if the capacitance is found to be 1.25x10-10F between two plates that are 1mm apart and the area shared by the plates is 20 square cm.

Q18. What is the energy stored in the capacitor in question 17 if the potential difference between the plates is 15V?

Q19.Define the following: Insulator, electric current.

Q20. Name the three effects of an electric current and give examples of where each can be shown.

Q21. What is the correct way to attach both an ammeter and a galvanometer to a standard circuit?

Q22. A current of 5 amps flows through a bulb, how much charge would flow through the bulb in 10 minutes?

Q23. How long does it take a current of 10 amps to transfer a charge 18KC?

Q24. Define direct and alternating current.

Q25. Draw the diagram of the setup of the apparatus you would use to prove the three factors affecting the capacitance of a parallel plate capacitor exist.


Section three Some Mechanics

 

Q1. Define each of the following: Displacment, a scalar, acceleration, momentum, weight, pressure, Archimedes principle, Boyle’s law, work, power.

Q2. A man raises a block of mass 100kg to a height of 30m in 10 seconds. Find the average power.

Q3. A stone is thrown vertically upward with an initial speed of 50m/s, find the greatest height reached?

Q4. Derive the third equation of motion.

Q5. A man try’s to open a window who's locking system can withstand a force of 5000N. He uses a crowbar of length 0.75m to the fulcrum. He applies a force of 150 newtons. The distance from the fulcrum to the window where the force is felt is 2cm. Will the man manage to break in?

Q6. Find the value of acceleration due to gravity on a planet who's radius is 2x108m and who's mass is 8x108kg. Use you answer to find the weight of a person of mass 80kg on this planet.

Q7. Find the gravitational force of attraction between two metal spheres of mass 120kg if the distance between the surface of the spheres is 2m and the radius of each is 0.5m.

Q8. A cube of side 20cm is placed at a depth of 1.2m in water. Find the pressure at the top and bottom of the block?

Q9. What is the difference between displacement and distance?

Q10. A man of mass 80kg mounts a staircase which is 3 m high he does this in 20 seconds. What power is being used by the man? 

Section Four More Revision

Q1. What type of wave is a sound wave. Name some features of this type of wave.
Q2. Define the following: overtones, loudness, resonance, threshold of hearing, sound intensity at a point, and fundamental frequency for an object.
Q3. If a wire is 2m long and has a mass of 0.25kg and is under tension of 150N. Calculate the fundamental frequency of vibration.
Q4. Define the following: diffraction grating, polarisation, dispersion, electromagnetic spectrum.
Q5. A diffraction grating has 550 lines per mm and the angle between the second order fringe to the right and the second order fringe to the left is 100 degrees. Find the wavelength of the light.
Q6. Define the following: conductor coulombs law, electric field.
Q7. Describe how you would charge an object using (just one) by induction. Use diagrams to aid your explanation.
Q8. Two charges of charge 10C are placed a distance of 3m apart. The permittivity of free space is 8.9x10-12 fm-1. The charges are in an environment which has a relative permittivity of 5. Find the force of attraction between the two charges.
Q9. A charge of 5 micro coulombs experiences a force of 50N when in an electric field. Find the electric field strength.
Q10. Find the electric field strength at a distance of 2m on a charge of size 3 micro coulombs in a material with permittivity of that of air which is 8.9x10-12 fm-1.

Q11. How would you use a gold leaf electroscope to test whether a charged rod is positively or negatively charged?

Q12. Coulombs law is an inverse square law. What does this term mean?

Q13. Define the following: Potential difference, Capacitance, the Farad.

Q14. Find the work done in bringing a charge of 3 Coulombs through a potential difference of 6 volts.

Q15. The capacitance of a Van de Graff generator is 3x10-11F and it usually reaches a voltage of 250 KV. Find the typical charge that would be present on the dome.

Q16. What are the factors that affect the capacitance of a parallel plate capacitor?

Q17. Find the relative permittivity of a medium if the capacitance is found to be 1.25x10-10F between two plates that are 1mm apart and the area shared by the plates is 20 square cm.

Q18. What is the energy stored in the capacitor in question 17 if the potential difference between the plates is 15V?

Q19.Define the following: Insulator, electric current.

Q20. Name the three effects of an electric current and give examples of where each can be shown.

Q21. What is the correct way to attach both an ammeter and a galvanometer to a standard circuit?

Q22. A current of 5 amps flows through a bulb, how much charge would flow through the bulb in 10 minutes?

Q23. How long does it take a current of 10 amps to transfer a charge 18KC?

Q24. Define direct and alternating current.

Q25. Draw the diagram of the setup of the apparatus you would use to prove the three factors affecting the capacitance of a parallel plate capacitor exist.

Section five. The electron and modern physics

Mass of electron = 1.6X10-19 .       Charge on electron = 9.1X10-31.  Mass of proton = 1.673493X10-27         Mass of lithium = 1.165007X10-26     Mass of Helium = 6.646322X10-27kg             Deuterium = 3.344X10-27kg

 

Q1. Give three properties of the electron.

Q2. Describe the working of the cathode ray tube. (use bullet points) Use a diagram if you wish.

Q3. Describe an experiment to show the photoelectric effect.

Q4. Find the energy of a photon with a wavelength of 5X10-7m.

Q5. Light with a wavelength of 1.8X10-7m falls on a metal and causes photoemmission. The current produced by the photoemmission is 0.5mA in a circuit. Find the light energy falling on the metal. Find how many electrons pass any part of the circuit in five seconds?

Q6. What are X rays? Give two properties also.

Q7. What were the conclusions of the Rutherford experiment?

Q8. Describe how the light from a laser if produced. (give the energy level background also)

Q9. If 232Th90 loses an alpha and two beta particles. What will the resulting isotope be? Show your work.

Q10. What is the unit of radioactivity? What does it mean?

Q11. What is the fuel usually found in a nuclear reactor? What is the function of the coolant in a reactor?  What is the function of the moderator in a reactor? 

Q12. If How much energy is released in the following reaction?       2H1 +2H1 >>>> 4He2.

Q13. Give some of the hazards of ionising radiation.

Section six Electron and Modern physics

Mass of electron = 1.6X10-19 .            Charge on electron = 9.1X10-31.

Mass of proton = 1.673493X10-27                              Mass of lithium = 1.165007X10-26                  Mass of Helium = 6.646322X10-27kg

Q1. What is thermionic emission?
Q2. Give three properties of cathode rays.
Q3. An electron is accelerated through 5000v what is the kinetic energy that it gains? Find also the velocity of the electron as it reaches the anode.
Q4. A photon has a wavelength of 8x10-9m. Find the energy of the photon in eV.
Q5. The work function of a particular metal is 1.2 ev. If light with a wavelength of 7x10-7m falls on the metal what is the maximum kinetic energy that an emitted electron can have?
Q6. Explain the set up of Rutherford's 1911 experiment. What observations did he make? What did he conclude?
Q7. Describe an experiment to show the existance of three individually distinct types of radioactivity.
Q8. Show the radioactive decay sequence for 238U92 to 230Th90 if it breaks down with an alpha and then a beta particle each time it undergoes a sequence of radioactive disintegration.
Q9. Give the function of each of the following components in a nuclear reactor. Control rods, shielding, moderator.
Q10. In the Walton and Cockroft experiment hydrogen nuclei were fired at a lithium target. Write an equation to represent what occurred in this reaction. Calculate the energy released in the reaction.
Q11. Name two instruments that can be used to detect nuclear radiation and in the case of one of these explain the principal by which it operates.
Q12. 0ne eighth of a radioactive isotope remains after 40 years. Find the decay constant of the isotope.

Section Seven Sample exam paper

Q1. A student calculated the acc due to gravity using the freefall method. Draw a diagram of the apparatus used in the experiment, on your diagram mark the displacement S of the ball. The following results were recorded. Graph the results and find g from the graph.

 s/cm 30    40    50    60   70     80    90

t/ms 244  291  325  342  371  409  420.List some errors that the student encountered. How could the student make the exp more accurate?

 

Q2. The laws of equilibrium for a set of coplanar forces were investigated. Draw a diagram of the apparatus setup. How did the student know that the stick was in equilibrium? If two up forces of 4.5 N and two downward forces of 4N hang on the horizontal stick what is the weight of the stick? Why was it important that the spring balances hung vertically from the stick?

A second set up was as follows                        position on metre stick/cm     11.5    26.2    38.3   70.4   80.2

Verify that the stick is in                                  magnitude of force/N             2.0      4.5      3.0     5.7     4.0

Equilibrium                                                         direction of force                down      up    down    up    down

 

Q3. The focal length of a concave mirror was found. Draw the diagram of the experimental setup. What were the main errors encountered. Why was the approx focal length measured before the experiment? The following results were found, graph them & find f from the graph

u/cm  15.0  20.0  25.0  30.0  35.0  40.0                                           How was the approximate focal length found?

v/cm  60.5  30.0  23.0  20.5  18.0  16.5                                           What is the significance of the x and y axis in this experiment?

 

Q4. A monochromatic light wavelength was measured. Draw the diagram of the apparatus setup. Why should the diffraction grating be perpendicular to the stage? What would the difference be if the student used a100 lines per mm over a 600 lines per mm diff grating? The students used a 300 line per mm diff grating The angle from the 2nd order image to the left and 2nd order image to the right was 40.6 degrees. Find the wavelength of the light. Describe how to set up a spectrometer.

 

Q5. A student measured the speed of sound in air. Draw a diagram to explain how the student found the results include the wave section in your diagram. What is end correction? How did the student vary the tube length? How did the student know that they had found the first harmonic? The diameter of the tube was found to be 2.05 cm what was used to find this? The following results were recorded.            

f/Hz        512     480     426                 Graph the results found and use your graph to find the speed of sound in air.

l/cm        16.0    17.2    19.4                     What errors did the student encounter during the experiment?

 

Q6. A student verified Joule’s law. Describe using a diagram how the experiment was carried out. Why was the current allowed to flow for a fixed time in each case. How would you make the experimental results more accurate and what errors did the student encounter during the experimental process? The student found the following results, graph them and explain why they verify Joule’s law.

I /A       1.5  2.0   2.5   3.0    3.5    4.0    4.5                What instrument was used to measure the current?

Δθ / °C 3.5  7.0  10.8  15.0  21.2  27.5  33.0  

 What instrument was used to keep the current steady. Why was the current trying to change?

 

Q7. Resistivtiy for a material wire was measured. What was used to measure the wire diameter? Why was it measured so many times? Draw a diagram of the set up of the experiment. What precautions should be taken when measuring the wire length and resistance? The following results were recorded. Resistance = 32.1 Ω.Length of wire = 90.1 cm  Wire diameter in mm= 0.19, 0.21, 0.20, 0.21, 0.20. Use the results to find the resistivity of the wire. What was used to measure the resistance of the wire? Give another way this could be done.

 

Q8. A student carried out an experiment to compare current against voltage for a bulb, metallic conductor, ionic solution and semicon. Draw the schematic of the experiment setup. Sketch and explain the graphs that the student obtained.

 

Q9. Give three properties of the electron.  

 If an electron enters a voltage of 10Kv what speed will it reach?    

What is thermionic emission? 

Explain using a diagram how you would show the photoelectric effect.     

Give an expression for the photoelectric effect.     

Define X rays.   

What are cathode rays?       Give some properties of cathode rays.  

 Light with frequency of 2.3 x 10 15Hz hits a zinc plate with a threshold frequency of 1.99X1015Hz what will the velocity of the emitted electron be?     Use a diagram to describe the operation of a CRT and an X ray machine.

 Name the three types of radiation and say what each type is made of.    Use two different diagrams that would allow you to show that there are indeed three different types of radiation.     

Describe the Rutherford experiment of 1919 with regard to what he did, what he observed and what he concluded.     If a radioactive particle has a half life of 30 minutes how much will remain active after 4 hours? Show the disintegration of 238U92 as it loses an alpha particle two beta particles and then another alpha particle.     

    238U92  Decays to 230Th90 how many alpha and beta particles has it lost?    

 What is conserved in a nuclear reaction?    

Why was the neutrino proposed and why did it take so long to detect it?     

 Write an expression that describes the experiment carried out by Cockroft and Walton verifying Eintein’s E= mc2 and calculate the energy released in the reaction.     Write an expression that describes a fusion reaction.    

 Find the energy released in a fusion reaction using the following information.  2H1 mass = 3.344x10-27kg      4He2 mass = 6.646x10-27kg.        Write an expression to describe pair production and and another to describe pair annihilation.       

Name two instruments used to detect nuclear radiation and describe how one of them works.             Define fission, fusion and the work function.

Give the quark composition of the meson and the Baryon. Name some mesons and baryons and give the quark composition of the one you named.

What is a Lepton name two?     What are Hadrons?    Give the four fundamental forces of nature and give three properties of each.

Q10. Describe how you would separate charges by induction. Describe how you would charge a single object by induction. 

Give three uses of the gold leaf electroscope.

 Define potential difference. 

Draw a diagram of the parallel plate capacitor and give three ways the capacitance of the capacitor could be increased. 

Find the energy stored in a capacitor with capacitance of 7F and PD of 25V. 

Name some sources of emf’s.

 Find the magnetic field strength at a distance of 6m from an 8 micro Coulomb charge. 

Define resistivity. 

Find the resistivity of a wire with diameter 0.1mm and resistance 25 ohm’s and length 90cm. 

 Describe an experiment to show an electric field pattern.

 Derive the formulae R = R1 + R2 and 1/R=1/R1 +1/R2 for resistors in series and in parallel. D

raw a diagram containing a 3 & 4 ohm resistor in parallel connected to a 12v battery. Calculate the current flowing through the 4 ohm resistor. Describe and experiment to show the principle of the ampere.

 Describe an experiment which will demonstrate that a current carrying conductor experiences a force. 

Define the following, Semiconductor, extrinsic conduction, intrinsic conduction, Doping, p-n junction.

 

Q11. What are the laws of electromagnetic induction and describe an experiment that describes each. 

Explain both the right and left hand laws with regard to electromagnetic induction. 

Describe the electric field around a solenoid and a coil. Give some functions of the earth’s magnetic field. 

Describe an experiment to show both mutual and self induction. 

A square coil of side 15cm enters a magnetic field of flux density 10T at an angle of 35 degrees with a speed of 2m/s. The coil has 200 turns. Find the induced emf in the coil.

 

Section Eight Semi conductors, Magnetism and electromagnetic induction. done

Q1. Explain what is meant by a semiconductor.

Q2. Explain the difference between intrinsic and extrinsic semiconductors.
Q3. Explain doping. Give the types of doping that exist and give examples of each type.
Q4. What is a magnetic field? How would you plot the magnetic field around a current carrying wire?
Q5. Explain Fleming’s left hand rule.
Q6. A wire of length 3m is placed at right angles to a magnetic field of flux density 3T. It is carrying a current of 5A. What is the force on the wire? If the wire was at an angle of 60 degrees to the perpendicular, what would the force on it be?
Q7. An electron enters a magnetic field at right angles to the field. The field has a magnetic flux density of 3T. What is the radius of the path it takes if its speed is 5x106 m/s.
Electron mass 9.1x10-31.    Charge 1.6x10-19.
Q8. Explain the laws of induction and draw the set up of the apparatus you would use to verify them.
Q9. Find the induced emf for a square loop of wire of side 10cm as it passes into a magnetic field of flux density 4T at an angle of 50 degrees to the perpendicular. It takes the loop one second to enter the field.
Q10. If the resistance of a coil is 20 ohms and the induced current in the coil is 0.5 amps as a magnet moves into it. Calculate the force that must be applied to the magnet if it is moving into the coil at a speed of 10m/s.
Q11. Draw a diagram to show how mutual induction can occur.
Q12. If a transformer has 700 turns in the primary coil and 200 turns in the secondary coil, calculate the output voltage if the transformer is hooked up to a 120 volt power supply.
Q13. Draw a sketch of the graph that would represent DC against time.
Q14. What function does the earth’s magnetic field serve?
Q15. What is the difference between a coil and a solenoid?

Section Nine Revision of Mechanics experiments.

    Experiment Revision Questions.  (Mechanics):

1.    Measure velocity and Acceleration.

2.    To verify the principle of conservation of momentum.

3.    To show that acceleration is proportional to force.

4.    Using a simple pendulum to find the relationship between length and period time and hence calculating acceleration due to gravity.

5.    Using a trapdoor and electromagnet to calculate acceleration due to gravity.

6.    To verify Boyle’s law.

7.    Co planar forces.

For each of the experiments above

-         Draw a diagram of the apparatus used.

-         If a graph was used in the experiment, sketch it.

-         How would the student make the experiment more accurate?

                  -         What errors did the student encounter when carrying out the experiment?   

                              Section Ten Try your hand at this mini exam paper.      

Mini exam paper 3.

Q. A student carried out an experiment to investigate the principle of conservation of momentum.

A track and trolleys were used. The mass of the trolleys were 550 grams each. The first trolley travelled 20cm and the student counted 20 gaps in the sulfur on the track. The first trolley the hit a second trolley which was at rest and they moved 18cm over 20 gaps on the track. What was the velocity of the first trolley before the crash? Use the information given to verify the principle of conservation of momentum. The result found were pretty close but not the same, explain how this could be accounted for. List the main errors in this experiment.

 

Q. The following is part of a student’s report of an experiment to verify joules law.

“A current I was passed through a heating coil placed in 100g of water in a calorimeter. The rise in temperature of the water was recorded. This was repeated using the same volume of water for different values of current for the same length of time”

The table shows the data recorded.

I =           0.75        1.0          1.25        1.5          1.75

q =          4.0          7.2          11.2        17.4        22.0

Draw a suitable graph on graph paper and explain how it verifies joules law.

Draw the circuit diagram for this experiment and explain the need for each component.

Q A student carried out an experiment to find the wavelength of monochromatic light using a diffraction grating containing 800 lines per mm. The angle between the first order omage on the left and the second order image on the right was found to be 32 degrees. 

Draw a diagram of the apparatus setup. Find the wavelength of the monochromatic light. Why would the student use a sodium light source rather than a white light source when carrying out the experiment. Describe the setup of the spectrometer for use in this expeiment.

 Q. Explain each of the following terms and give examples. Lepton, hadron, baryon, meson, elementary particle, scintillation.

Name and give the charge on the different types of quark. Give the quark composition of a proton, neutron and their anti particles.

Explain the Walton and Cockroft experiment. Give an equation for what happened. Name the quantities conserved in a nuclear reaction. Name the four fundamental forces of nature and give two properties of each. Explain the terms pair production and annihilation.

 

Q. Give some properties of the electron. Explain the term thermionic emission.

After thermionic emission an electron enter a potential difference of 8kv. What energy does the electron gain? What speed is it traveling leaving the high voltage? If the electron then enters a magnetic field at right angles to the field and starts to move in a circle of radius 1x10-8m what is the strength of the magnetic field?

Explain the photoelectric effect. If this occurs to a metal with a work function of 2ev as a result of light with wavelength 600nm falling on it, give the kinetic energy of the emitted electron.

What is Einstein's photoelectric law?

 

Q. What are the laws of electron magnetic induction?

A loop of wire enters a magnetic field of flux density 8.5T, perpendicular to the field. It enters the field at a speed of 5m\s, and it takes 2 seconds to enter fully. Find the emf induced in the field.

What is the moment of force when the loop becomes parallel to the field. Explain your answer.

 

Q. Draw a transformer. If it has 500 turns in the primary coil and 100 in the secondary, calculate the output when the transformer is hooked up to the mains. State Lenz's law. What happens when you bring a magnet toward a suspended aluminum ring at high velocity?

If an rms current is 3A find the actual current. If you have a voltage of 4V what is the rms voltage?

Why do rms values exist? Explain mutual and self induction give a diagram.

 

Q.Draw a diagram of a circuit with two 12v batteries in series , two resistors one 20ohms the other 15 ohms in parallel and a further resistor in series with resistance 30 ohms. Find the current flowing in the circuit. Find the current flowing in the 15 ohm resistor.

 

Q. Explain the Rutherford experiment. Name the three  types of radiation and say what they are made up of. Show experimentally that there are three. Show penetrating power.  Show 238U92 disintegrating by losing an alpha and beta particle. A radioactive isotope has a half life of 10 years how much is left after 30 years? An alpha emitter has a half life of 8X108 years find the number of particles being emitted from a sample containing 2.5X1025 atoms. Name two instruments used to detect radiation. Explain one. What is fission and fusion? Name the parts and function of a nuclear reactor.

 

Q.. If a wire is 2m long and has a mass of 0.25kg and is under tension of 150N. Calculate the fundamental frequency of vibration.
Define the following: diffraction grating, polarisation, dispersion, electromagnetic spectrum.
 A diffraction grating has 550 lines per mm and the angle between the second order fringe to the right and the second order fringe to the left is 100 degrees. Find the wavelength of the light.
 Define the following: conductor coulombs law, electric field.
Describe how you would charge an object using (just one) by induction. Use diagrams to aid your explanation.
Two charges of charge 10C are placed a distance of 3m apart. The permittivity of free space is 8.9x10-12 fm-1. The charges are in an environment which has a relative permittivity of 5. Find the force of attraction between the two charges.

Find the electric field strength at a distance of 2m on a charge of size 3 micro coulombs in a material with permittivity of that of air which is 8.9x10-12 fm-1.

Coulombs law is an inverse square law. What does this term mean?

Section Eleven. Electricity and Magnetism.

Q1.

Draw a diagram of a circuit which contains a 20 volt power supply and two resistors one of resistance 450 ohms and the other with resistance 300 ohms. The resistors should be in parallel with eachother.

Find the overall resistance in the two resistors.

Find the overall current flowing through the circuit.

Find the current flowing through the 450 ohm resistor.

 

Q2.

Find the induced emf flowing through a loop that enters a magnetic field of flux density 7T. The loop is square of side 20cm and it takes 0.5 of a second for it to enter the loop. The loop also enters the magnetic field at an angle of 70 degrees to the perpendicular.

 

Q3. State the effects of an electric current and give one example of where each occurs.

 

Q4. Draw two graphs below one show the relationship between AC and time and the other showing DC against time.

AC                                                                              DC

+                                                                                  +

!                                                                                   !

!                                                                                   !

!                                                                                   !

-------------------------------------------                              -----------------------------------------------------

!                                                                                   !

!                                                                                   !

!                                                                                   !

-         Time                                                                      -                                   Time

 

Q5.Explain with the aid of a diagram how mutual induction can occur.

 

Q6.Lots of different materials conduct electricity. Draw a sketch of the graph of current against voltage for the following:

 

Metal at constant temperature.           A filament bulb.    A semiconductor diode.    A gas.

 

Q7. A wind turbine supplies power to a house of two kilowatts at a voltage of 120v, through a 4mm cable of resistivity 5x10-8ohm meters. The cable is 0.5km in length.

Find the resistance of the Cable.

What is the current when the turbine is at this level of production?

Energy is lost through the cable on transmission. In what form is the energy lost?

How could the energy loss be reduced?

 

Q8. Draw a diagram of a Wheatstone bridge with R1= 10 R2= 20 R3= 5 and R4= 11 ohms.

Is the bridge balanced? Show your work.

 

Q9.State Coulombs law.         

Find the force of attraction between two particles with charge 5 micro coulombs that are 77cm apart in a substance with permittivity of 75. Permittivity in vacuum is 8.9X10-12fm-1.

 

Q10. A charge of 2 micro coulombs enters a PD of 1500V. The particle has a mass of 22x10-32kg.

Find the speed that the particle reaches in the PD.

Section twelve Some Question five practice.

. State Newton’s gravitational law and state what each part in the equation represents.

. Derive Newton’s third equation of motion.

. Derive the formula g = GM/ r2.

. What is a thermometric property?

. What is the thermometric property of the following? Mercury, Alcohol, thermocouple, semiconductor diode.

. A square box of side 30cm and weight 50N is at a depth of 12m under water. Find the pressure at the top and bottom of the box and hence the force at the top and bottom. Will the box sink or float?

. A square loop of side 15cm enters a magnetic field of magnetic flux density 5T. It is traveling at 2ms-1 and has 100 turns. Find the induced emf in the loop.

. Why do people who work with integrated circuits connect themselves to the earth?

. How do we know that light is a transverse wave?

. What is polarization?

. What is meant by the term pair annihilation? Give an equation that could represent this.

. What is meant by pair production? Give an equation that could represent this.

. The distance between a node and the nearest anti node on a wave is 25cm. Find the frequency of the wave if it is travelling at 50ms-1.

. State the laws of refraction.

. By what means does information pass through a fibre optic cable?

. A stone is thrown vertically upward with a speed of 120 ms-1. What is the greatest height it will reach and how long will it take for this to occur?

. How would you show the resultant of three vectors in the lab?

. A gun of mass 20kg fires a bullet of mass 10g at a velocity of 250ms-1. Find the recoil speed of the gun.

. In sound what are the properties of waves that effect volume, Pitch and quality?

. Draw a diagram of a wave vibrating at the 1st harmonic in a tube closed at one end.

. What is meant by intrinsic semi conduction?

. Find the acceleration due to gravity of a body which is 285km above the earth’s surface. Radius of earth is 6.4X106 m. Earth mass 6X1024kg

. Name the nearest star to the earth.

. Define potential difference and work.

. What is the right hand grip rule?

. State Flemming’s left hand law.

. What is the force of attraction between two 6 micro coulomb forces which are 3m apart and separated by air.

. What is the force of attraction between two 500kg masses located 2m from each other.

. Draw a diagram of the magnetic field around a solenoid.

. How is a depletion layer formed in a semiconductor?

. State the law of floatation.

. Define the critical angle with regard to light.

. What is self induction?

. When is a rigid body said to be in equilibrium?

. State Lenz’s law of electromagnetic induction.

. State the four fundamental forces of nature and give the distances over which they act.

. Why is the photoelectric effect often said to be the opposite of x ray production?

. What is meant by the threshold frequency?

. State Boyle’s law. What is the principal of operation of a heat pump in a refrigerator?

.What is the difference between sound intensity and sound intensity level? Give the units of both.

. If the capacitance of a capacitor is 2 micro farads and a voltage of 20v, find the energy stored.

Section Thirteen Semiconductors and magnetism

Q1. What is a semiconductor?

Q2. Explain the difference between intrinsic and extrinsic conduction in semi conductors.

Q3. Draw a labelled diagram of the crystal lattice that would be formed if phosphorus was used to dope silicon.

Q4. What type of doping is the doping in Q3 above?

Q5. Describe how a depletion layer is formed.

Q6. Draw a diagram of a circuit containing a battery a bulb a switch and a diode in forward bias.

Q7. How would you show the magnetic field around a bar magnet in the lab? (Diagram)

Q8. How would you plot the electric field around a wire conductor? (Diagram)

Q9. Explain the right hand grip rule with regard to an electric field.

Q10. Explain the difference between true north and magnet north.

 

Q11. How does the earths magnetic field work? 

Section Fourteen SHM Heat & Waves

Values:       Speed sound in air 340m/s
              Specific heat capacity of water: 4180 j/kg/k

              Specific heat vaporisation 2.3x10 6 j kg k

                    Specific heat fusion ice 3.3x10 5 j kg k


Q1.state Hookes law.

Q2. Define simple harmonic motion.

Q3. A particle moving with simple harmonic motion makes 20 full oscillations in 8 seconds. Find the frequency of the motion.

Q4. The period of a particle in SHM is 4 seconds what is the acceleration of the particle when it is 12.5 cm from the position of equilibrium?
Q5. What is a thermometric property?

Q6. Explain the difference between heat and temperature.

Q7. Convert 13 degrees celcius to kelvin.
Q8. How much heat is needed to heat 2kg of water from 10 degrees celcius to 90 degrees?

Q9. How much energy is required to heat ice from -10 degrees celcius to 20 degrees if the mass of the ice is 3kg?
Q10. Define the terms:  specific latent heat of vapourisation, conduction, solar constant, U value.

Q11. Explain the difference between longitudinal and transverse waves with regard to their motion.

Q12. How would you prove that light travels as a transverse wave?

Q13. Explain the following terms: interference, coherent wave sources, diffraction, polarization

Q14. As a person stands on a platform, she hears a train approaching which seems to have a frequency of 1300 Hz. This frequency seems to change to a frequency of 900 Hz after the train has passed. 6ind the velocity at which the train was traveling and the actual frequency of the sound emitted by the train.

Q15. A bat emits a high pitched noise that hits a wall and returns to the bat 8.5 seconds later> how far from the wall is the bat?

 

Section 15 Static & Capacitance

Q1. What is static electricity?

Q2. Find the force between two charges in a vacuum. The charges are both positive and carry charges of 3 and 2 Coulombs respectively. The distance between the charges is 2m.

Q3. Describe how you would separate the charges on two metallic, insulated spheres using induction.

Q4. What is an electric field?

Q5. Describe an experiment that would show the direction of electric field lines.

Q6. If a charge of 6 micro-coulombs is a distance of 2.2m from an electric field find the electric field strength.

Q7. A diffraction grating has 500 lines per mm. The angle from the second order fringe to the right to the second order fringe to the left is 60 degrees. Calculate the wavelength of the light.

Q8. What is the significance of the fact that light can be polarised?

Q9. State the adjustments that should be made to a spectrometer before use.

Q10. A capacitor of capacitance 2 uF is charged to a potential difference of 200 Volts. Find the energy stored in it.

Q11. List the factors that affect the capacitance of a parallel plate capacitor.

Q12.   The plates of an air filled parallel plate capacitor have a common area of 40 cm2 and are 1 cm apart.

The capacitor is connected to a 12 V d.c. supply.

Calculate

(i)                  the capacitance of the capacitor;

(ii)               the magnitude of the charge on each plate.

 

Section 16 Semiconductors, electromagnetic Induction & Resistance

Q1. What is the difference between a coil and a solenoid?

Q2. Derive the formula for resistors in seriesl with each other in a circuit.
Q3. Calculate the resistivity of a wire of length 85cm and diameter 0.25mm and resistance 30 ohms.

Q4. Explain what is meant by doping in semiconductors. Give examples of different types of doping.

Q5. What is rectification when mentioned in circuitary.

Q6. What is the difference between magnetic flux density and magnetic flux?

Q7. Draw a diagram of a circuit which contains a 20 volt power supply and two resistors one of resistance 450 ohms and the other with resistance 300 ohms. The resistors should be in parallel with each other.

Q8. for Q7 above.

Find the overall resistance in the two resistors.

Find the overall current flowing through the circuit.

Find the current flowing through the 450 ohm resistor.

Q9. a coil with 170 turns enters a magnetic field of flux density of 9.5T at an angle of 25 degrees to the perpendicular. The coil is of a square of side 8.5cm. The coil is travelling with a velocity of 0.75 m/s. Find the induced emf in the coil.

Q10. How can you tell by looking at it, that the four resistors in a Wheatstone bridge are balanced? Give one use for a Wheatstone bridge.