Physical Science-Hewitt Reading Ch. 23

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

A battery produces DC. A generator at a power station produces AC.

What condition is necessary for the sustained flow of water in a pipe? What analogous condition is necessary for the sustained flow of charge in a wire?

A difference in pressure is necessary for the sustained flow of water in a pipe. A potential difference in the analogous condition for sustained flow of charge in a wire.

What exactly is an ampere?

An ampere is a rate of flow of 1 coulomb of charge per second.

What is an electric circuit?

An electric circuit is any path along which electrons can flow.

Name two kinds of practical "electric pumps"

Batteries and electric generators are two kinds of "electric pumps".

Does charge flow through a circuit or into a circuit? Does voltage flow through a circuit, or is voltage established across a circuit?

Charge flows through a circuit. Voltage is established across a circuit.

What is the function of fuses or circuit breakers in a circuit?

Fuses and circuit breakers are devices which keep electric circuits from getting overloaded.

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

Heating a metal wire increases electrical resistance.

What is the error in saying that electrons in a common battery-driven circuit travel at about the speed of light?

It is the electric signals travel at nearly the speed of light.

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

Kilowatt and watt are units of power and kilowatthour is a unit of energy.

As more lanes are added to toll booths, the resistance of vehicles passing through is reduced. How is this similar to what happens when more branches are added to a parallel circuit?

Resistance lowers in parallel circuits as branches are added because there are more paths for the current to flow along.

For a given voltage, what happens to the amount of current flows in your skin when you perspire?

The amount of current that flows in your skin when you perspire increases because the resistance decreases.

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?

The current would drop to half its previous value.

What is meant by drift velocity?

The drift velocity is the average speed of the electrons as they flow through an electric circuit.

From where do the electrons originate that produce an electric shock when you touch a charged conductor?

The electrons that produce an electric shock when I touch a charged conductor come from me.

What property of a diode enables it to convert ac to pulsed dc?

The property of only allowing electron flow in one direction enables it to convert ac to pulsed dc.

What is the function of the round third prong in a modern household electric plug?

The round third plug connects an electrical appliance to the ground. This allows any excess buildup in charge to be sent to ground and prevent accidental shock.

What is the error in saying the source of electrons in a circuit is the battery or generator?

The source of the electrons in a circuit is the conducting material in a circuit not the battery.

In a circuit of two lamps in parallel, if there is a voltage of 6 V across one lamp, what is the voltage across the other lamp?

The voltage drop across the other lamp in the circuit is 6 V because the voltage drop across devices in parallel are equal.

If voltage of 6 V is impressed across the above circuit and the voltage acres the first lamp is 2 V, what is the voltage across the second lamp? Defend your answer.

The voltage drop across the second lamp in the circuit must be 4 V because the sum of the voltage drops across the devices in a circuit must equal the supplied voltage. 6 V = 2 V + 4V