Electricity- electric current (12)

Question 1

What is electric current? State its units

Answer 1

The rate of flow of charge. It is measured in amperes (amps)

Question 2

What is potential difference?

Answer 2

The work done moving a unit charge between 2 points in a circuit
V = W/Q

Question 3

What is resistance?

Answer 3

How difficult it is for current to flow through an appliance.
A component has a resistance of 1 ohm if 1 amp flows through it when a p.d of 1 volt is applied across it
R = V/I

Question 4

What is meant by an ohmic conductor?

Answer 4

A conductor that obeys Ohm’s law, meaning that current is directly proportional to potential difference providing physical conditions (such as temperature) remain constant

Question 5

How can you measure the current in a circuit?

Answer 5

You can measure the current with an ammeter connected in series with the component

Question 6

How do you measure potential difference across a component?

Answer 6

Using a voltmeter, connected in parallel across the component being measured

Question 7

What does the gradient of a current-potential difference graph represent?

Answer 7

Rate of change of current with respect to voltage.

This is not the same as 1/R

Question 8

What does an ohmic conductor look like?

Answer 8

The line has a constant gradient and passes throught the origin. This shows that voltage is directly proportional to current

Question 9

What common appliance would have a s-shaped graph

Answer 9

A filament lamp. As the current increases the resistance also increases. A big increase in voltage produces only a small increase in current