Electromagnetic induction is the process of generating:
a) Electric charge due to magnetic field
b) Magnetic field due to electric charge
c) Electric current due to magnetic field
d) Magnetic field due to electric current
Answer: c) Electric current due to magnetic field
According to Faraday’s law of electromagnetic induction, the induced electromotive force (emf) is proportional to:
a) The strength of the magnetic field
b) The velocity of the conductor
c) The area of the conductor
d) The rate of change of magnetic flux
Answer: d) The rate of change of magnetic flux
Lenz’s law states that the direction of the induced current in a conductor is such that it:
a) Opposes the motion of the conductor
b) Supports the motion of the conductor
c) Depends on the resistance of the conductor
d) Depends on the voltage applied to the conductor
Answer: a) Opposes the motion of the conductor
The phenomenon of self-induction occurs when:
a) A changing current in one coil induces a current in another coil
b) A changing magnetic field induces a current in the same coil
c) A magnetic field is produced due to the flow of current in a coil
d) A changing magnetic field induces a voltage in a nearby coil
Answer: b) A changing magnetic field induces a current in the same coil
The unit of magnetic flux is:
a) Tesla
b) Weber
c) Henry
d) Volt
Answer: b) Weber
A transformer works based on the principle of:
a) Electromagnetic induction
b) Electrostatic induction
c) Magnetic permeability
d) Magnetic hysteresis
Answer: a) Electromagnetic induction
The primary coil of a transformer is connected to a 120V AC power supply and has 1000 turns. If the secondary coil has 2000 turns, what is the voltage across the secondary coil?
a) 120V
b) 240V
c) 60V
d) 480V
Answer: b) 240V
The primary coil of a transformer has 500 turns and is connected to a 240V AC power supply. If the secondary coil has 1000 turns, what is the voltage across the secondary coil?
a) 120V
b) 240V
c) 480V
d) 960V
Answer: c) 480V
The step-up transformer is used to:
a) Increase the voltage and decrease the current
b) Decrease the voltage and increase the current
c) Increase the voltage and increase the current
d) Decrease the voltage and decrease the current
Answer: a) Increase the voltage and decrease the current
The step-down transformer is used to:
a) Increase the voltage and decrease the current
b) Decrease the voltage and increase the current
c) Increase the voltage and increase the current
d) Decrease the voltage and decrease the current
Answer: b) Decrease the voltage and increase the current
In a transformer, if the primary coil has more turns than the secondary coil, the transformer is called:
a) Step-up transformer
b) Step-down transformer
c) Isolation transformer
d) Auto transformer
Answer: b) Step-down transformer
In a transformer, if the secondary coil has more turns than the primary coil, the transformer is called:
a) Step-up transformer
b) Step-down transformer
c) Isolation transformer
d) Auto transformer
Answer: a) Step-up transformer
The efficiency of a transformer is given by the ratio of:
a) Output power to input power
b) Input power to output power
c) Voltage across the primary coil to voltage across the secondary coil
d) Current through the primary coil to current through the secondary coil
Answer: a) Output power to input power
The magnetic field inside a solenoid can be increased by:
a) Increasing the current flowing through the solenoid
b) Increasing the number of turns in the solenoid
c) Decreasing the length of the solenoid
d) Increasing the resistance of the solenoid
Answer: b) Increasing the number of turns in the solenoid
A coil is placed in a magnetic field. If the number of turns in the coil is doubled, the induced emf will:
a) Double
b) Halve
c) Remain the same
d) Increase by a factor of four
Answer: a) Double
The phenomenon of electromagnetic induction is used in:
a) Electric motors
b) Generators
c) Transformers
d) All of the above
Answer: d) All of the above
An AC generator converts:
a) Mechanical energy into electrical energy
b) Electrical energy into mechanical energy
c) Heat energy into electrical energy
d) Sound energy into electrical energy
Answer: a) Mechanical energy into electrical energy
In an AC generator, the frequency of the generated alternating current depends on:
a) The speed of rotation of the coil
b) The strength of the magnetic field
c) The number of turns in the coil
d) All of the above
Answer: a) The speed of rotation of the coil
The direction of the induced current in an AC generator changes:
a) Every half-cycle
b) Every quarter-cycle
c) Every full cycle
d) It does not change
Answer: b) Every quarter-cycle
A coil is rotated in a magnetic field. The magnitude of the induced emf can be increased by:
a) Increasing the speed of rotation
b) Increasing the number of turns in the coil
c) Increasing the strength of the magnetic field
d) All of the above
Answer: d) All of the above
An electric motor converts:
a) Electrical energy into mechanical energy
b) Mechanical energy into electrical energy
c) Heat energy into electrical energy
d) Sound energy into electrical energy
Answer: a) Electrical energy into mechanical energy
The direction of the force experienced by a current-carrying conductor placed in a magnetic field can be determined using:
a) Fleming’s left-hand rule
b) Fleming’s right-hand rule
c) Lenz’s law
d) Faraday’s law
Answer: b) Fleming’s right-hand rule
The speed of an electric motor can be increased by:
a) Increasing the current flowing through the motor
b) Increasing the voltage applied to the motor
c) Increasing the number of turns in the motor coil
d) All of the above
Answer: c) Increasing the number of turns in the motor coil
A generator and a motor are essentially the same device, but their operation is:
a) Inverse to each other
b) Independent of each other
c) Identical to each other
d) Unrelated to each other
Answer: a) Inverse to each other
The phenomenon of electromagnetic induction is based on the law of conservation of:
a) Energy
b) Charge
c) Momentum
d) Mass
Answer: a) Energy
A coil of wire is connected to a galvanometer. If a magnet is moved towards the coil, the galvanometer will show:
a) A momentary deflection in one direction
b) A momentary deflection in the opposite direction
c) No deflection
d) A continuous deflection
Answer: a) A momentary deflection in one direction
A coil of wire is connected to a galvanometer. If a magnet is moved away from the coil, the galvanometer will show:
a) A momentary deflection in one direction
b) A momentary deflection in the opposite direction
c) No deflection
d) A continuous deflection
Answer: b) A momentary deflection in the opposite direction
The strength of the induced emf can be increased by:
a) Increasing the speed of the magnet
b) Increasing the number of turns in the coil
c) Increasing the strength of the magnet
d) All of the above
Answer: d) All of the above
The phenomenon of electromagnetic induction is used in the functioning of:
a) Electric power plants
b) Electric generators
c) Electric transformers
d) All of the above
Answer: d) All of the above
A transformer has 500 turns in the primary coil and 1000 turns in the secondary coil. If the voltage across the primary coil is 100V, what is the voltage across the secondary coil?
a) 50V
b) 100V
c) 200V
d) 400V
Answer: c) 200V
A transformer has 200 turns in the primary coil and 400 turns in the secondary coil. If the voltage across the primary coil is 120V, what is the voltage across the secondary coil?
a) 30V
b) 60V
c) 120V
d) 240V
Answer: d) 240V
A coil of wire is placed in a changing magnetic field. The induced current in the coil can be increased by:
a) Increasing the resistance of the coil
b) Increasing the number of turns in the coil
c) Increasing the velocity of the coil
d) All of the above
Answer: b) Increasing the number of turns in the coil
The concept of mutual induction is based on the principle of:
a) Faraday’s law
b) Lenz’s law
c) Coulomb’s law
d) Ohm’s law
Answer: a) Faraday’s law
The direction of the induced current in a coil can be determined using:
a) Lenz’s law
b) Coulomb’s law
c) Ampere’s law
d) Ohm’s law
Answer: a) Lenz’s law
A changing magnetic field can induce an emf in a conductor by:
a) Moving the conductor in the magnetic field
b) Moving the magnetic field around the conductor
c) Changing the intensity of the magnetic field
d) All of the above
Answer: d) All of the above
The direction of the induced current in a coil can be reversed by:
a) Reversing the magnetic field
b) Reversing the direction of motion of the coil
c) Increasing the resistance of the coil
d) Increasing the number of turns in the coil
Answer: a) Reversing the magnetic field
The strength of the induced emf can be increased by:
a) Increasing the speed of the motion
b) Increasing the strength of the magnetic field
c) Increasing the number of turns in the coil
d) All of the above
Answer: d) All of the above
A transformer has an efficiency of 90%. If the input power is 100W, what is the output power?
a) 10W
b) 90W
c) 100W
d) 110W
Answer: b) 90W
A transformer has an efficiency of 80%. If the input power is 200W, what is the output power?
a) 40W
b) 160W
c) 200W
d) 250W
Answer: b) 160W
The primary coil of a transformer has 200 turns and is connected to a 240V AC power supply. If the secondary coil has 1000 turns, what is the voltage across the secondary coil?
a) 12V
b) 24V
c) 120V
d) 240V
Answer: c) 120V
