Electric current. potential difference and resistance

Question 1

charge carrier

Answer 1

a charged particle that contributes to an electric current; these may be electrons, protons or ions

Question 2

quantised

Answer 2

a quantity is said to be quantised when it has a definite minimum magnitude and always comes in multiples of that magnitude

Question 3

current

Answer 3

the rate of flew of electric charge past a point

Question 4

ampere

Answer 4

the SI unit of electric current

Question 5

coulomb

Answer 5

one coulomb is the charge that flows past a point in a circuit in a time of 1s when the current is 1A

Question 6

elementary charge

Answer 6

e = 1.6 × 10^-19 C

Question 7

number of density

Answer 7

the number of charge carriers, such as free electrons, per unit volume in a material.

Question 8

mean drift velocity

Answer 8

the average speed of a collection of charged particles when there is a current in a conductor

Question 9

electric current

Answer 9

I= nAvq

Question 10

homogenous

Answer 10

for an equation to be valid the units must be homogeneous, which means that units, when reduces to the base units, are the same for each term in the equation

Question 11

potential difference

Answer 11

the potential difference, V, between two points, A and B, is the energy transferred per unit charge as it moves from point A to point B.

Question 12

e.m.f

Answer 12

the energy transferred per unit charge in driving charge round a complete circuit

Question 13

electrical resistance

Answer 13

the ratio of potential difference to current. Unit: ohm

Question 14

ohm

Answer 14

the ohm is the resistance of a component when a potential difference of 1 volt drives a current of 1 ampere through it