PHYSICS: CH 25 QUIZ QUESTIONS

A transformer transforms voltage while

transferring energy from one coil to another.

Neon signs require about 12,000 volts to operate. If the circuit uses a 120 volt power source, the ratio of primary to secondary turns (loops) on the transformer should be

1 primary to 100 secondary

A step-up transformer steps up voltage by ten times. Neglecting slight losses, if 100 W of power go into the primary coil, the power coming from the secondary coil is

100W

A step-up transformer steps up voltage by ten times. If the voltage input is 120 volts, the voltage output is

1200V

The voltage across the input terminals of a transformer is 120 V. The primary has 25 loops and the secondary has 50 loops. The voltage the transformer delivers is

240V

When a magnet is moved to and fro inside a wire coil, voltage is induced. If the coil has twice as many loops, the voltage induced is

2x as much

Four amperes of current exist in the primary coil of a transformer. The voltage across the primary coil is 120 V. What is the power output of the secondary coil?

480W

The voltage across the input terminals of a transformer is 120 V. The primary has 50 loops and the secondary has 25 loops. The voltage the transformer delivers is

60V

Voltage can be induced in a wire by

All of the above: moving a magnet near the wire moving the wire near a magnet changing the current in a nearby wire

When a change occurs in the magnetic field in a closed loop of wire

All of the above: a voltage is induced in the wire a current is created in the loop of wire electromagnetic induction occurs

An electric motor is very similar to

An electric generator

Compared to the primary voltage, the secondary voltage of a transformer can be

Any of the above: Higher Lower The same

The output power of an ideal transformer is

Equal to the input power

If you thrust a magnet into the opening of a rubber band, the rubber band will

None of the above: Rotate Have a current in it

Electromagnetic induction occurs in a coil of wire when there is a change in

The magnetic field in the coil

When voltage is induced in a coil of wire, current is

also induced

Magnetic field strength inside a current-carrying coil will be greater if the coil encloses

an iron rod

Transformers use ac to satisfy the required

change in magnetic field for operation

The principle difference between a step-up and step-down transformer is

different ratios of turns (loops) of wire for each

A device that transforms mechanical energy into electrical energy is a

generator

If you thrust a magnet into a closed loop of wire, the loop will

have a current in it

The primary of a transformer

may or may not have an iron core

A device that transforms electrical energy into mechanical energy is a

motor

The rate at which energy is transferred is

power

When a bar magnet is thrust into a coil of copper wire, the coil tends to

repel the magnet as it enters

If the voltage produced by a generator alternates, it does so because

the changing magnetic field that produces it alternates.

A transformer actually transforms

voltage