Required Peactical: Combinations of Resistors in Series and Parallel

Aim

how combination of resistors in series + parallel affect total R

Independant

no. of resistors

Dependant

Total resistance

Control

p.d. power supply, temp. resistors

Method

1. Connect series circuit with ammeter, battery and switch + resistor. Voltmeter in parallel.

2. Close switch + record readings

3. Repeat 1+2 for 2nd resistor

4. Connect both resistor in series and voltmeter in parallel to both.

5. Close switch and record readings.

6. Arrange resistors in parallel

7. Close switch and record readings

Analysis

• series

  • resistance of the combined resistors is equal to the sum of the two individual resistances

  • electrons flow in one path through both resistors, so the current does too

• parallel

  • resistance of the combined resistors is less than the sum of the two individual resistances

  • electrons are split between the different paths but the resistors still have the same potential difference across them

Systematic error

• crocodile clip at 0- zero error

  • ammeter + voltmeter at 0

Random error

• small I so temp doesn’t rise+ change R

• I off between readings

Safety

• don’t touch hot wire

• no liquids close to equipment