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Physics
UTME / JAMB 2025
Electromagnetic Field
Solution
The device that operates using the magnetic effect of electric current is
A
Rheostat
B
Thermostat
C
Electric bell
D
Carbon microphone
medium Difficulty
Study Explanation
Physics
WAEC / WASSCE 2025
Electromagnetic Field
Solution
2a. State Faraday's law of electromagnetic induction.
b. Draw a labelled diagram of an induction coil and explain how it works.
c. How is the effect of eddy currents minimized in the coil?
d. State two reasons why a capacitor should be included in the primary circuit of the coil.
e. State three uses of an induction coil.
medium Difficulty
Study Explanation
Physics
UTME / JAMB 2024
Electromagnetic Field
Solution
Which of the following operates based on magnetic effect of electric current?
A
electric heater
B
photocell
C
Dynamo
D
Cold cathode
medium Difficulty
Study Explanation
Physics
UTME / JAMB 2024
Electromagnetic Field
Solution
If a charge ion goes through a combined electric field E and magnetic field B, the resultant emergent velocity of the ion is
A
\(\frac{E}{B}\)
B
EB
C
\(\frac{B}{E}\)
D
E-B
medium Difficulty
Study Explanation
Physics
UTME / JAMB 2024
Electromagnetic Field
Solution
An ideal transformer has
A
Maximum primary resistance
B
No flux leakage
C
Hysteresis
D
Eddy current
medium Difficulty
Study Explanation
Physics
UTME / JAMB 2024
Electromagnetic Field
Solution
Which of the following measuring instruments operates based on the heating effect of electric current?
A
moving iron ammeter
B
hot wire ammeter
C
galvanometer
D
electric heater
medium Difficulty
Study Explanation
Physics
UTME / JAMB 2024
Electromagnetic Field
Solution
As per Faraday's laws of electromagnetic induction, an e.m.f is induced in a conductor whenever
A
lies parallel to the magnetic flux
B
lies in a magnetic field
C
lies out side but close to a magnetic field
D
cuts magnetic flux
medium Difficulty
Study Explanation
Physics
WAEC / WASSCE 2024
Electromagnetic Field
Solution
Which of the following modes is the most economical method of transmitting electrical power over a long distance?
A
Alternating current at high voltage and low current.
B
Alternating current at low voltage and high current.
C
Direct current at high voltage and low current.
D
Direct current at low voltage and high current.
medium Difficulty
Study Explanation
Physics
UTME / JAMB 2023
Electromagnetic Field
Solution
A step-down transformer is used on a 2.2 kV line to deliver 110 V. How many turns are on the primary windings if the secondary has 25 turns?
A
20
B
250
C
200
D
500
medium Difficulty
Study Explanation
Physics
UTME / JAMB 2023
Electromagnetic Field
Solution
A generator manufacturing company accidentally made an AC generator instead of a DC generator. To fix this error,
A
the magnetic field needs to be made stronger
B
the split rings should be replaced with slip rings
C
the number of turns of the armature coil needs to be decreased
D
the slip rings should be replaced with split rings
medium Difficulty
Study Explanation
Physics
WAEC / WASSCE 2022
Electromagnetic Field
Solution
The reason for having a large number of turns in the coil of a moving coil galvanometer is to--------
A
make the deflection of the needle proportional to the current
B
increase the sensitivity of the galvanometer
C
decrease the magnetic flux produced by the magnet
D
make the permanent magnet stronger
medium Difficulty
Study Explanation
Physics
WAEC / WASSCE 2022
Electromagnetic Field
Solution
Current is passed through two parallel conductors in the same direction. If the conductors are placed near each other, they will------------------
A
move in a circle
B
repel each other
C
remain stationary
D
attract each other
medium Difficulty
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Physics
WAEC / WASSCE 2022
Electromagnetic Field
Solution
Which of the following statements about a straight current-carrying wire placed in a uniform magnetic field is correct? The wire experiences ---------------
A
maximum motor force if the current reverses its direction
B
no motor force of it is parallel to the field
C
no motor force if it is perpendicular to the field
D
a motor force with constant direction if either the current or the magnetic field is reversed
medium Difficulty
Study Explanation
Physics
WAEC / WASSCE 2020
Electromagnetic Field
Solution
An electrical device has 50 turns in its primary coil and 20 turns in the secondary coil. The device can be a\an?
A
step-up transformer
B
step-down transformer
C
d.c generator
D
a.c generator
medium Difficulty
Study Explanation
Physics
UTME / JAMB 2019
Electromagnetic Field
Diagram
Solution
A coil X is moved quickly away from the end Y of a stationary metal bar and a current then flows in X as shown above.
Then
A
the bar is not a magnet
B
Y is a north pole
C
Y is a South pole
D
Y repels coil X
medium Difficulty
Study Explanation