H Exp – Electricity and Electronics 12 – Response of resistance in a variable frequency a.c. circuit

Aim – To establish a relationship between the current through a resistor and the frequency of the a.c. supply.

Instructions

Click on the right of the output voltage dial to increase the output voltage.
Click on the left of the output voltage dial to decrease the output voltage.
The signal generator frequency can be increased or decreased in the same way.

▪ Select a suitable output voltage so that the current through the resistor and the oscilloscope trace can easily be observed.
▪ Note the current and height of the oscilloscope trace (which is a measure of the output voltage).
▪ Increase the signal generator frequency and note any effect on the ammeter. Ensure the output voltage remains constant.
▪ Continue to increase the signal generator frequency.
▪ State if the resistance of a resistor is affected by the frequency of the a.c. supply.
▪ State why it is important that the output voltage remains constant.

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