Exam Chapters 22-25 Review
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 on the transformer should be:
1:100.
When a 60-watt light bulb is connected to a 120-volt source the current in the light bulb is:
0.5 A.
The principle advantage of ac power over dc power is that:
Ac voltage can be transformed via conventional transformers.
An electron is shot through a spot somewhere between the ends of a horseshoe magnet. The electron:
Direction is changed.
The source of all magnetism is:
Moving electric charge.
A wire carrying a current is normally charged:
Not at all.
The intensity of cosmic rays bombarding the Earth's surface is largest at the:
Poles.
A positive ion has more:
Protons than electrons.
After a capacitor is fully charged, the total umber of electrons it contains:
Remains unchanged.
A difference between gravitational and electrical forces is that electrical forces:
Repel or attract.
The ratio of the potential difference across a metallic conductor to the current in the conductor is known as?
Resistance.
The magnetic field strength inside a current-carrying coil will be greater if the coil encloses a:
Rod of iron.
A transistor is an example of a:
Semiconductor.
An iron rod becomes magnetic when?
The net spins of its electrons are in the same direction.
A transformer actually transforms
Voltage.
The number of electrons delivered daily to an average American home by an average power utility in the mid 1980s was:
Zero.
When a car is struck by lightning, the resulting electric field inside the car is:
Zero.
Heat a copper wire and its electric resistance:
increases.
Rapid change of a magnetic field induces
An electric field
Moving electric charges will interact with:
An electric field or a magnetic field.
An electric motor is very similar to:
An electric generator.
When a bar magnet is broken in two, each half is?
At most half as strong as the original magnet.
An electron and a proton:
Attract each other.
Like kinds of magnetic poles repel while unlike kinds of magnetic poles:
Attract.
When the distance between two charges is halved, the electrical force between the charges:
Quadruples.
Two protons attract each other gravitationally and repel each other electrically. By far the greater force is:
The electrical repulsion.
Compared to the amount of electric current in the filament of a lamp, the amount of current in the connecting wire is:
The same.
Disconnect a small-voltage battery from a coil of many loops of wire and a large voltage is produced by:
The sudden collapse in the magnetic field.
If a magnet is pushed into a coil, voltage is induced across the coil. If the same magnet is pushed into a coil with twice the number of loops:
Twice as much voltage is induced.
The power dissipated in a 4-ohm resistor carrying 3 A is:
36 W.
A certain transformer doubles input voltage. If the primary coil has 10 A of current, then the current in the secondary coil is
5 A.
Electrons are made to flow in a wire when there is:
A potential difference across its ends.
The unit of electric charge, the coulomb, is the charge on:
A specific large number of electrons.
Thrust a magnet into a coil of wire and the coil:
Becomes electromagnetic and has current in it.
Electrons move in an electrical circuit:
By interacting with an established electric field.
To say that electric charge is conserved is to say that electric charge:
Can neither be created or destroyed.
Transformer use ac so there will be the required
Change in magnetic field for operation.
Which statement is correct?
Charge flows in a closed circuit.
Magnetic field lines about a current-carrying wire:
Circle the wire in closed loops.
Which force binds atoms together to form molecules?
Electrical,
When there is a change in the magnetic field in a closed loop of wire:
Electromagnetic induction occurs, a current is created, and a voltage is induced in the wire.
Metal detectors, like the ones used at airports, are activated by?
Electromagnetic induction.
The output power of an ideal transformer is
Equal to the input power.
Compared to the huge force that attracts an iron tack to a strong magnet, the force that the tack exerts on the magnet is?
Equally huge.
Superconducting electromagnets:
Exist now.
Alternating current is normally produced by a:
Generator.
Magnetic domains normally occur in:
Iron.
To say that electric charge is quantized is to say that the charge on an object:
Is a whole-number multiple of the charge of one electron.
To say that an object is electrically polarized is to say:
Its charges have been rearranged.
Compared to he primary voltage, the secondary voltage may be
Larger, smaller, or the same.
