Light globe filament resistance

In this experiment you will vary the voltage across a mini light globe to obtain measurements of current and voltage across the globe. You will then plot the current versus voltage graph and analyse its non-ohmic nature.

Equipment

Battery in holder, variable resistor, voltmeter, ammeter, wires, mini globe, breadboard.

Method

• 1. Set up the following circuit. (It may help you to connect the variable resistor first and the voltmeter last.or

Take the measurements of I (current) for the at least five values of V (voltage) between 0.0V and 0.50V, at least five values between 0.50V and 1.0V and at least five values between 1.0 and 5.0 V. ( you may find it difficult to adjust the variable resistor to get exact voltages, this is why you are being asked to find five between two values)

Questions

6. How many joules per second are being dissipated by the globe at 5.0 V?

7. In what form is this energy?