How should the student change the circuit to give negative values for current andpotential difference?

To obtain negative values for current and potential difference in a circuit, the student should reverse the connections to the power supply or battery. This means connecting the positive terminal of the power supply to the negative side of the circuit and the negative terminal of the power supply to the positive side of the circuit. This will reverse the direction of the current flow and the polarity of the potential difference, making them negative.

Here are the steps:

1. Identify the positive and negative terminals of your power supply or battery. The positive is usually marked with a plus (+) sign and the negative with a minus (-) sign.

2. Disconnect the power supply from the circuit.

3. Reconnect the power supply in reverse, i.e., connect the positive terminal of the power supply to the negative side of the circuit and the negative terminal of the power supply to the positive side of the circuit.

4. Check the current flow and potential difference with an ammeter and voltmeter respectively. They should now read negative values.

Remember to always take safety precautions when working with electrical circuits.