Core Practical 3 - Determine the EMF and Internal Resistance of an Electrical Cell Flashcards
1
Q
What is the aim of this core practical?
A
To Determine the EMF and Internal Resistance of an Electrical Cell
2
Q
What equipment is required for this practical?
A
- voltmeter
- ammeter
- battery with internal resistance
- variable resistor
3
Q
What are the 2 methods for this practical ?
A
- Finding current and voltage for a certain value of load resistance and plotting V = e - Ir
- Work out power dissipated and plot power dissipated against load resistance (power dissipated is at max when load resistance is equal to internal resistance)
4
Q
Do both methods use the same setup and procedure?
A
Yes
5
Q
What is the procedure?
A
Vary resistance using the variable resistor and measure pd and current for the value
6
Q
What do we need to do to get greater accuracy?
A
- add a switch and break the circuit between readings
- check for zero errors on ammeter and voltmeter
- Could use a multimeter as it is difficult to read meters simultaneously when there are fluctuating readings on the meters
- add a voltmeter around the terminals of the cell (although some volts will be lost)
7
Q
Do we need repeated readings?
A
NO
