Resistance

Question 1

What resistance do ohmic conductors have?

Answer 1

Ohmic conductors have a constant resistance.

Question 2

What does the resistance not do in an ohmic conductor?

Answer 2

The resistance of an ohmic conductor doesn’t change with the current

Question 3

What happens to the energy when electrical charge flows through the filament lamp?

Answer 3

It transfers some energy to the thermal energy store of the filament which is designed to heat up.

Question 4

What happens to resistance and current when you increase the temperature?

Answer 4

Resistance increases with temperature, so as the current increases the filament lamp heats more and the resistance increases.

Question 5

For diodes what does resistance depend on?

Answer 5

The resistance depends on the direction of the current.

Question 6

In diodes what direction does current flow in?

Answer 6

The current flows in one direction but have a very high resistance if it’s reversed.

Question 7

Investigating resistance

Answer 7

Method:
1. Attach a crocodile clip to the thin wire, level with 0cm on the ruler
2. Attach with the second crocodile clip to the wire e.g 10cm from the first clip.
Note down there length of wire between the clip.
3. Close the switch, then record the current through the wire and the potential difference across it.
4. Open the switch then move the second crocodile clip, e.g another 10cm along the wire.
Close the switch again, then record the new length, current and potential difference.
5)Repeat this for different lengths of the test wire.
6) use your measurements of current and potential difference to calculate resistance
V= I x R
7) plot a graph of resistance against wire length and draw a line of best fit.