Chapter 23 Electric Current

Question 1

Potential difference

Answer 1

The difference in electric potential between two points, measured in volts. When two points of different electric potential are connected by a conductor, charge flows so long as a potential difference exists. (Synonymous with voltage difference.)

Question 2

Electric current

Answer 2

The flow of electric charge that transport energy from one place to another. Measured in amperes, where 1A is the flow of 6.25 x 10^18 electrons per second, or 1 coulomb per second.

Question 3

Electrical resistance

Answer 3

The property of a material that resists electric current. Measure in ohms.

Question 4

Ohm’s Law

Answer 4

The statement that the current in a circuit varies in direct proportion to the potential different or voltage across the circuit and inversely with the circuit’s resistance.

Current = voltage/ resistance

A potential difference of 1 V across a resistance of 1 ohm produces a current of 1 A.

Question 5

Direct current (dc)

Answer 5

Electrically charged particles flowing in one direction only.

Question 6

Alternating current (ac)

Answer 6

Electrically charged particles that repeatedly reverse direction, vibrating about relatively fixed positions. In the US, the vibrational rate is commonly 60Hz.

Question 7

Electric power

Answer 7

The rate of energy transfer, or the rate of doing work; the amount of energy per unit time, which electrically can be measured by the product of current and voltage.

Power = current x voltage

Electric power is measured in watts (or kilowatts), where 1 A x 1 V = 1 W

Question 8

Series circuit

Answer 8

An electric circuit in which electrical devices are connected along a single wire such that the same electric current exists in all of them.

Question 9

Parallel circuit

Answer 9

An electric circuit in which electrical devices are connected in such a way that the same voltage acts across each one and any single one completes the circuit independently of all the others.