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
