Chapter 23 Physics - Electric Current

How much energy is supplied to each coulomb of charge that flows through a 12-V battery?

12 joules

A diode converts ac to pulsed dc. What electrical device smooths the pulsed dc to a smoother dc?

A capacitor

Between a watt, a kilowatt, and a kilowatt-hour, which is a unit of power and which is a unit of energy?

A watt is power, a kilowatt is power, and a kilowatt-hour is energy

Why are electrons, rather than protons, the principal charge carriers in metal wires?

Electrons are free to move through the metal, whereas protons are fixed in place

At what speed do electrons in a battery driven automotive circuit travel along a wire? At what speed does the electric field propagate along a wire?

Electrons move at 0.01 cm/s. The electric field propagates at nearly the speed of light

If the resistance of a circuit remains constant while the voltage across the circuit decreases to half its former value, what change occurs in the current?

It cuts in half

Does heating a metal wire increase or decrease its electrical resistance? Why?

It increases resistance because atoms at higher temperatures jostle into the way of moving electrons

Why does a wire that carries electric current become hot?

Moving electrons collide with atoms, which transfers their kinetic energy to atomic motion

Does a battery produce dc or ac? Does the generator at a commercial power station produce dc or ac?

The battery is dc; the generator is ac

What is meant by drift velocity?

The net flow of electrons along a wire