series and parallel resistance practical

Aim

how combination of resistors in series + parallel affect total R

Independant

no. of resistors

Dependant variable

Total resistance

Control variable

p.d. power supply, temp. resistors

Step 1

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

Step 2

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

Step 3

Repeat 1+2 for 2nd resistor

Step 4

Close switch + record readings

Step 5

Close switch and record readings.

Step 6

Arrange resistors in parallel

Step 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

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