Electromagnetic Induction

Multiple Choice

The magnetic field strength of a solenoid can be increased by

• placing a copper rod in the solenoid.

• decreasing the resistance of the solenoid.

• decreasing the number of turns on the solenoid.

• decreasing the potential difference between the ends of the solenoid

Multiple Choice

Two parallel wires carrying current in the same direction will repel each other.

• TRUE

• FALSE

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Multiple Choice

According to Faraday’s Law, what is the magnitude of the induced e.m.f. in a circuit directly proportional to?

• The rate of change of magnetic flux in the circuit

• The strength of the electric field

• The resistance of the conductor

• The length of the conductor

Multiple Select

Which of the following statements about electromagnetic induction are correct?

• A changing magnetic field induces a current in a conductor.

• A constant magnetic field induces a current in a conductor.

• Electromagnetic induction is the process of producing an induced e.m.f. due to a changing magnetic field.

• A galvanometer deflects when a magnet is moved in and out of a coil.

Multiple Choice

According to Faraday’s law, what happens to the induced e.m.f. when the magnet is moved faster in and out of the solenoid?

• The induced e.m.f. increases.

• The induced e.m.f. decreases.

• The induced e.m.f. remains the same.

• No e.m.f. is induced.

Multiple Choice

How would you reverse the direction of the current flowing through the coil in Faraday's experiment?

• a. Use a magnet of opposite polarity

• b. Move the magnet through the coil faster

• c. Reverse the magnet's direction

• d. Use a larger magnet

Multiple Choice

How would flipping the magnet in this experiment change the current?

• The current would not change
• The current would go to the right
• There would be no current
• The current would go oscillating.

Multiple Choice

What is the direction of the induced magnetic field?

• Left
• Right
• Up
• Down

Multiple Choice

What is the direction of the induced magnetic field?

• Left
• Right
• Up
• Down

Multiple Choice

In what direction is the magnet moving?

• Left
• Right
• Up
• Down

Multiple Select

Which of the following statements correctly describe what happens when a magnet is dropped through a copper tube?

• A current is induced in the copper tube.

• The induced current produces a magnetic field that opposes the motion of the magnet.

• The magnet falls at the same rate as it would in air.

• The magnet speeds up as it falls through the tube.

Multiple Select

Which of the following are required to describe a simple a.c. generator as mentioned in the learning outcomes?

• Rotating coil or rotating magnet

• Slip rings (where needed)

• Permanent magnets only

• Graph of voltage output against time

Multiple Choice

When a coil is held stationary in magnetic field, the induced current in it:

• continuously changes

• randomly changes

• remains zero

• becomes maximum

Multiple Choice

The Fleming's right-hand rule is used when ....

• motion causes current

• current causes motion

• current causes potential difference

• motion causes magnetic field

Multiple Choice

In the picture shown, what will be the direction of the current in wire MN?

• Upward

• Downward

• Into the paper

• Out of the paper

Multiple Choice

Which of the following is a key principle behind the operation of transformers in power substations?

• Electromagnetic induction

• Thermal conduction

• Chemical reaction

• Mechanical rotation

Multiple Choice

A transformer does not change the following:

• Frequency

• Voltage

• Current

• None of these

Multiple Choice

This picture is an example of a ___________

• Step- Up Transformer
• Step- Down Transformer
• Motor
• Generator

Multiple Choice

Laminated insulation are normally used in the transformer:

• To reduce the hysteresis effect

• To increase the hysteresis effect

• To reduce the effect of eddy current

• To increase the effect of eddy current

Multiple Choice

Assume primary has 240 turns and secondary has 60 turns. Primary is connected with 120V AC power supply. What is the voltage on the secondary?

• 30 V

• 0.333 V

• 2 V

• 120V

Multiple Choice

If the primary power of an ideal transformer having a 2:1 voltage ratio is 100 W, the secondary power is:

• 200 W

• 75 W

• 50 W

• 100 W

Multiple Choice

What is the advantage of electricity transmission at high voltage?

• Increase the energy

• High current flow

• Reduce the heat dissipated in the electrical cable

• Reduce the resistance of transmission cable

Multiple Choice

Electricity is sent over ............... transmission lines.

• low voltage

• no voltage

• high voltage

Multiple Choice

Power supply network consists of

• Power stations - step-up transformers - transmission lines - step-down transformers - consumers

• Power stations - transmission lines - step-up transformers - consumers - step-down transformers

• Power stations - step-down transformers - transmission lines -step-up transformers - consumers

• Power stations - step-up transformers - consumers - transmission lines - step-down transformers