topic 3

Question 1

current

Answer 1

rate of flow of charge
SI unit - C/s

Question 1

potential difference

Answer 1

work done per unit charge

SI unit - J/C

V = W/Q

Question 2

drift velocity

Answer 2

the velocity of the charge carriers
- I = nqvA (current depends on the mean drift velocity)
- directly proportional to current

Question 3

relationship between the quantities

Answer 3

1) doubling charge carriers doubles current

Question 10

resistance

Question 11

three things that determine resistance

Answer 11

• length - longer the wire the more difficult it is to make a current flow
  
  • area - The wider the wire the easier it is for current to flow
  • resistivity - depends on the material the wire is made from

Question 12

resistivity

Answer 12

the resistance of a 1m length with a 1m2 cross-sectional area
measured in ohm metres

Question 13

Ohm’s law

Answer 13

provided the temperature is constant, the current through an ohmic conductor is directly proportional to the potential difference across it

Question 14

finding resistivity

Question 19

lost volts

Answer 19

energy that is wasted when overcoming internal resistance

Question 20

e.m.f

Answer 20

total amount of work done

Question 21

terminal p.d.

Answer 21

work done when 1 Coulomb of charge flows through load resistance

Question 22

what causes internal resistance

Answer 22

the chemical energy that makes electrons move