10.3 B Direct current work and power of current practical task 2 variant

Calculating power: Practical 2.13

You are going to investigate the power rating of different domestic appliances.

·      domestic appliances to test

·      power meters

·      stop clock

1.   Connect each appliance in turn to the power meter.

2.   Note the potential difference (this should be the same for each appliance) and the current drawn by each appliance and record these readings in the table.

3.   Leave the columns for power, resistance and power calculated from I²R blank for the moment.

1.   The power rating of each appliance can be calculated by:

power = potential difference × current

Calculate the power rating of each appliance and write the values in the table.

2.   The resistance of each appliance can be calculated by:

resistance = potential difference ÷ current

Calculate the resistance of each appliance and write the values in the table above.

3.   It can be shown that the power of each appliance can also be calculated by:

power = (current)² × resistance

Use this equation to calculate the power of each appliance and write the values in the
table above.

Do your values for power agree?