Mid-Cycle 5 Practice A

What is the primary function of an electric generator?

• To convert electrical energy into mechanical energy

• To convert mechanical energy into electrical energy

• To store electrical energy

• To amplify electrical signals

Which component in an electric motor is responsible for creating a magnetic field?

• Commutator

• Armature

• Stator

• Rotor

How does a transformer change the voltage in a circuit?

• By changing the frequency of the current

• By using electromagnetic induction between coils

• By converting AC to DC

• By storing energy in capacitors

In an MRI machine, what is the role of the magnetic field?

• To generate images by aligning hydrogen atoms in the body

• To heat the body tissues for better imaging

• To convert sound waves into images

• To measure electrical activity in the brain

Which law explains the principle of electromagnetic induction?

• Ohm's Law

• Faraday's Law

• Coulomb's Law

• Newton's Law

Describe how Faraday's Law is applied in the functioning of an electric generator.

• It uses a chemical reaction to produce electricity.

• It involves the rotation of a coil within a magnetic field to induce an electromotive force.

• It stores energy in a magnetic field.

• It uses solar panels to convert light into electricity.

What is the main difference between a step-up and a step-down transformer?

• A step-up transformer increases voltage, while a step-down transformer decreases voltage.

• A step-up transformer decreases voltage, while a step-down transformer increases voltage.

• A step-up transformer changes AC to DC, while a step-down transformer changes DC to AC.

• A step-up transformer stores energy, while a step-down transformer releases energy.

Explain how the direction of induced current is determined in electromagnetic induction.

• By the direction of the magnetic field lines

• By the speed of the moving conductor

• By Lenz's Law, which states that the induced current will oppose the change in magnetic flux

• By the temperature of the conductor

What is the role of the commutator in an electric motor?

• To convert AC to DC

• To reverse the direction of current in the armature windings

• To increase the speed of the motor

• To store electrical energy

Calculate the induced electromotive force (EMF) in a coil with 50 turns, if the magnetic flux changes by 0.1 Wb in 2 seconds.

• 2.5 V

• 5 V

• 10 V

• 25 V