Voltage - Current Characteristics for a Filament Lamp

This is a different way to connect the circuit. This is better than before because you can apply voltages right down to 0V

Connect the power pack to 12V d.c.

Add the push switch. This could also be an ordinary switch because we know the bulb will get hot anyway in this experiment.

Add the rheostat by connecting to the two coil ends. 1 2 2 1

Add the ammeter and ray box bulb. Connect to one end of the rheostat coil and to the rheostat slider 1 3 3 1

Finally add the voltmeter Test the circuit. Both meters should show positive readings. If not, reverse the leads.

Take about 10 readings by putting the slider in different positions.

Now reverse the power pack leads so the current flows the other way Both meters should now show negative readings

Take about 10 negative readings by putting the slider in different positions.

Now plot a graph of Voltage vs Current Current (A) Draw the best smooth curve through your points