- A transformer with 4200 turns in the primary coil operates a 240V mains supply and gives an
output of 8.0V. Determine the number of turns in...(Solved)
A transformer with 4200 turns in the primary coil operates a 240V mains supply and gives an
output of 8.0V. Determine the number of turns in the secondary coil (assuming it is 10% efficient)
Date posted: April 5, 2019. Answers (1)
- Two fixed resistors one of 100 ohms and the other of unknown resistance are connected in parallel.
The combination is placed in a circuit and current...(Solved)
Two fixed resistors one of 100 ohms and the other of unknown resistance are connected in parallel.
The combination is placed in a circuit and current passing through the combination was
measured for various p.d. The graph in figure 10 below drawn to scale shows the results:-
(i) From the graph, calculate the total resistance of the combination
(ii) Determine the value of the unknown resistance
Date posted: April 5, 2019. Answers (1)
- The diagram figure below shows a photocell connected in a circuit:-(Solved)
The diagram figure below shows a photocell connected in a circuit:-
(i) Complete the diagram by indicating the correct polarities in the gap for current to flow in
the circuit.
(ii) State and explain the effect of using light of different wave lengths on the amount of
current flowing in the circuit given that the distance of the source of light remains the same
Date posted: April 5, 2019. Answers (1)
- In an experiment using a photo cell, ultra violet light of varying frequency strikes a metal
surface. The maximum Kinetic energy (KE max) of the frequency...(Solved)
In an experiment using a photo cell, ultra violet light of varying frequency strikes a metal
surface. The maximum Kinetic energy (KE max) of the frequency F is measured. The graph
below shows how the maximum kinetic energy varies with frequency F
Use the graph to determine:-
i) Threshold frequency F
ii) The plank’s constant, h
iii) Work function of the metal
Date posted: April 5, 2019. Answers (1)
- The diagram below represents a cathode ray oscilloscope (CRO)(Solved)
The diagram below represents a cathode ray oscilloscope (CRO)
i) Name the parts labeled A and B
ii) What are the functions of C and D?
iii) State how electrons are produced
iv) Give a reason why the tube is evacuated.
Date posted: April 5, 2019. Answers (1)
- State one reason why a C.R.O is a more accurate voltmeter than a moving coil voltmeter(Solved)
State one reason why a C.R.O is a more accurate voltmeter than a moving coil voltmeter
Date posted: April 5, 2019. Answers (1)
- The graph below shows the relation between the stopping potential, Vs and the frequency of radiation when a certain surface is illuminated with light of...(Solved)
The graph below shows the relation between the stopping potential, Vs and the frequency of radiation when a certain surface is illuminated with light of different frequencies
From the graph determine:-
(i) The threshold frequency
(ii) The value of plank’s constant (e = 1.6 x 10-19C)
(iii) The work function of the material
Date posted: April 5, 2019. Answers (1)
- The time base of a CRO is 25ms/div while its gain is 2.5V/div. Use this information to
answer the questions that follow:
(Solved)
The time base of a CRO is 25ms/div while its gain is 2.5V/div. Use this information to
answer the questions that follow:
i) Calculate the frequency of the signal
ii) What is the peak voltage of the signal
Date posted: April 5, 2019. Answers (1)
- Explain why a magnetic field is used in the TV deflection system instead of an electric field(Solved)
Explain why a magnetic field is used in the TV deflection system instead of an electric field
Date posted: April 5, 2019. Answers (1)
- Name one factor that determines the velocity of photoelectrons produced on a metal surface
when light shine on it(Solved)
Name one factor that determines the velocity of photoelectrons produced on a metal surface
when light shine on it
Date posted: April 5, 2019. Answers (1)
- Calculate the wavelength of Green light whose energy is 3.37 x 10-19 J .
(h = 6.63 x 10-34JS, C = 3.0 x 108m/s)(Solved)
Calculate the wavelength of Green light whose energy is 3.37 x 10-19 J .
(h = 6.63 x 10-34JS, C = 3.0 x 108m/s)
Date posted: April 5, 2019. Answers (1)
- The variation of frequency f with the maximum kinetic energy Ek of the emitted electrons is shown on the graph below:(Solved)
The variation of frequency f with the maximum kinetic energy Ek of the emitted electrons is shown on the graph below:
Find:
(i) the value of the Planck’s constant h
(ii) the work function, Wo
Date posted: April 5, 2019. Answers (1)
- The solid of mass 12kg, weighs 100N and 94N when fully immersed in water and liquid L respectively. Calculate:-(Solved)
The solid of mass 12kg, weighs 100N and 94N when fully immersed in water and liquid L respectively. Calculate:-
(i) The density of the liquid in S.I units
(ii) The density of the solid
Date posted: April 5, 2019. Answers (1)
- Define thermionic emission.(Solved)
Define thermionic emission.
Date posted: April 5, 2019. Answers (1)
- An electrical heater is rated 3.45KW. The heater is immersed in 2.4kg of water.Calculate the minimum time it takes for the temperature of the water...(Solved)
An electrical heater is rated 3.45KW. The heater is immersed in 2.4kg of water.Calculate the minimum time it takes for the temperature of the water to rise from 23.0oC to 69.0oC. (Specific heat capacity of water = 4.2Jg/K)
Date posted: April 5, 2019. Answers (1)
- An electric kettle rated 3.0Kw, 240V is filled with water. If the water boiled after 8 minutes
of heating, determine the energy used in boiling the...(Solved)
An electric kettle rated 3.0Kw, 240V is filled with water. If the water boiled after 8 minutes
of heating, determine the energy used in boiling the water.
Date posted: April 5, 2019. Answers (1)
- An electric kettle is rated 3KW, 250V. Determine the resistance of the coil(Solved)
An electric kettle is rated 3KW, 250V. Determine the resistance of the coil
Date posted: April 5, 2019. Answers (1)
- An electrical immersion heater is rated 3kW, 250V. Choose a suitable fuse from 3A, 5A, 10A,
12A, and 20A that can be used in such an...(Solved)
An electrical immersion heater is rated 3kW, 250V. Choose a suitable fuse from 3A, 5A, 10A,
12A, and 20A that can be used in such an appliance.
Date posted: April 5, 2019. Answers (1)
- An electric bulb is rated 40W, 240V. What is the resistance of its filament?(Solved)
An electric bulb is rated 40W, 240V. What is the resistance of its filament?
Date posted: April 5, 2019. Answers (1)
- Given that a lamp is rated 45W 240V. Calculate the resistance of the heating element.(Solved)
Given that a lamp is rated 45W 240V. Calculate the resistance of the heating element.
Date posted: April 5, 2019. Answers (1)