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- A Power station has an input of 30kw at a potential difference of 5kv.A transformer with a secondary coil of 1000 turns is used to...(Solved)
A Power station has an input of 30kw at a potential difference of 5kv.A transformer with a secondary coil of 1000 turns is used to step down the voltage to 1000v for transmission along a grid .Assuming there are no power loses in the transformer .calculate.
i) current in the primary coil
ii) The number of turns in the primary coil
iii) The current in the secondary coil
iv) State which of the coils is thick and why
Date posted: May 31, 2019. Answers (1)
- The graph below shows the relationship between the voltage drop across a certain capacitor and the charge stored in the capacitor.
From the graph calculate the...(Solved)
The graph below shows the relationship between the voltage drop across a certain capacitor and the charge stored in the capacitor.
From the graph calculate the capacitance of the capacitor.
Date posted: May 31, 2019. Answers (1)
- The diagram below shows a circuit containing three capacitors.
i) Write an expression for effective capacitance between X and Y.
ii) If c1=6µF, c2=4.5µF and c3=5 µF,...(Solved)
The diagram below shows a circuit containing three capacitors.
i) Write an expression for effective capacitance between X and Y.
ii) If c1=6μF, c2=4.5μF and c3=5 μF, calculate the charge stored when point XY is connected in series with a battery of 6V
Date posted: May 31, 2019. Answers (1)
- Show the charge distribution on the hollow conductor shown below if it is positively charged.(Solved)
Show the charge distribution on the hollow conductor shown below if it is positively charged.
Date posted: May 31, 2019. Answers (1)
- The circuit set up shown below makes a current of 1A to flow through the 4O resistor
Calculate;
i) The current through the 2O resistor
ii) the...(Solved)
The circuit set up shown below makes a current of 1A to flow through the 4Ω resistor
Calculate;
i) The current through the 2Ω resistor
ii) the E.M.F of the cell given that the internal resistance is negligible
Date posted: May 31, 2019. Answers (1)
- A charge of 4.8C flows through a lamp every second. Calculate the number of electrons involved per second.(Solved)
A charge of 4.8C flows through a lamp every second. Calculate the number of electrons involved per second.
Date posted: May 31, 2019. Answers (1)
- The figure below shows a ray of light incident on a water-air interface from a source 8m deep.
i) Ray A is observed to bend as...(Solved)
The figure below shows a ray of light incident on a water-air interface from a source 8m deep.
i) Ray A is observed to bend as it enters the air. Give a reason why this occurs
ii) If the refractive index of water is 1.35, calculate the angle of refraction of ray A
iii) Find the critical angle of water
iv) Give a reason why ray B is not travelling out of water
v) A fish is placed at the source of light ray. Calculate the maximum area of view on the surface of water
Date posted: May 31, 2019. Answers (1)
- The figure below shows a simple electric motor. Study the figure and answer the questions that follow.
i) Indicate on the diagram the direction of rotation...(Solved)
The figure below shows a simple electric motor. Study the figure and answer the questions that follow.
i) Indicate on the diagram the direction of rotation of the coil.
ii) Explain how the motor works specifying clearly the functions of the parts P and Q.
iii) State one way by which the speed of this motor can be increased.
Date posted: May 31, 2019. Answers (1)
- The figure below shows two parallel conductors P and Q carrying current in the same direction.
On the same figure;
i) sketch the magnetic field pattern
ii)...(Solved)
The figure below shows two parallel conductors P and Q carrying current in the same direction.
On the same figure;
i) sketch the magnetic field pattern
ii) Indicate the force F due to the current on the conductor
Date posted: May 31, 2019. Answers (1)
- The graph in the figure below shows variation in activity of a sample of a radioactive material.
Use the graph to determine the half life of...(Solved)
The graph in the figure below shows variation in activity of a sample of a radioactive material.
Use the graph to determine the half life of the sample
Date posted: May 31, 2019. Answers (1)
- The diagram below shows an object placed in front of two mirrors inclined to each other at an angle x
An observer sees five images, determine...(Solved)
The diagram below shows an object placed in front of two mirrors inclined to each other at an angle x
An observer sees five images, determine the value of angle x?
Date posted: May 31, 2019. Answers (1)
- The figure below Shows a source of beta particles and a detector being used to check the thickness of paper in a paper mill.
i) Explain...(Solved)
The figure below Shows a source of beta particles and a detector being used to check the thickness of paper in a paper mill.
i) Explain how the device works.
ii) Explain why beta particles are used instead of alpha particles or gamma rays.
Date posted: May 31, 2019. Answers (1)
- The diagram below shows waves being diffracted.
What adjustments should be done to obtain the wave form below?(Solved)
The diagram below shows waves being diffracted.
What adjustments should be done to obtain the wave form below?
Date posted: May 31, 2019. Answers (1)
- The figure below shows a section of a house wiring.
i) Name
The circuit labelled X
The terminals A and B.
ii) State the function of P...(Solved)
The figure below shows a section of a house wiring.
i) Name
The circuit labelled X
The terminals A and B.
ii) State the function of P in the circuit.
iii)Give a reason why P is on A but not B.
iv) Explain why earthing is necessary in such a circuit.
Date posted: May 31, 2019. Answers (1)
- Gamma, radio, infrared, x-rays are part of the electromagnetic spectrum.
i) Arrange these radiations in order of increasing energy
ii) State how radio waves are detected(Solved)
Gamma, radio, infrared, x-rays are part of the electromagnetic spectrum.
i) Arrange these radiations in order of increasing energy
ii) State how radio waves are detected
Date posted: May 31, 2019. Answers (1)
- The diagram below shows a current carrying conductor placed in a magnetic field.
i) Show on the diagram the direction of force on the conductor
ii)...(Solved)
The diagram below shows a current carrying conductor placed in a magnetic field.
i) Show on the diagram the direction of force on the conductor
ii) If the current through the conductor is reduced, state and explain what happens to the force in (i) above.
Date posted: May 31, 2019. Answers (1)
- The figure below shows a three pin plug wired by a student and connected to an appliance rated 1000W, 240V.
State two mistakes made by the...(Solved)
The figure below shows a three pin plug wired by a student and connected to an appliance rated 1000W, 240V.
State two mistakes made by the student in the wiring.
Date posted: May 31, 2019. Answers (1)
- A photo sensitive cathode of work function 2.1 eV is illustrated with a radiation of wavelength 4.5× 10-7. Determine the stopping potential for the cathode....(Solved)
A photo sensitive cathode of work function 2.1 eV is illustrated with a radiation of wavelength 4.5× 10-7. Determine the stopping potential for the cathode. Speed of light C = 3.0 × 108m/s,1 eV = 1.6 × 10-19j,
h = 6.6 × 10-34Js.
Date posted: May 31, 2019. Answers (1)
- The figure shows an apparatus used to investigate photoelectric effect.
i) Name the parts A and B.
ii) State the function of C.(Solved)
The figure shows an apparatus used to investigate photoelectric effect.
i) Name the parts A and B.
ii) State the function of C.
Date posted: May 31, 2019. Answers (1)
- The figure shows a loudspeaker producing sound waves in air.
i) Explain how compression and rarefactions are formed.
iii) The wavelength of the waves produced is...(Solved)
The figure shows a loudspeaker producing sound waves in air.
i) Explain how compression and rarefactions are formed.
iii) The wavelength of the waves produced is 0.4m. Determine the frequency of the waves if the speed of sound in air is 330m/s.
Date posted: May 31, 2019. Answers (1)