Testing Components Flashcards

All 5 cards in this deck

How is an ammeter connected in a circuit used to test a component?

In series with the component, so it measures the current through it.

True or false? A voltmeter is connected in parallel with the component whose potential difference is being measured.

True. It measures the p.d. across the component, so it goes across it.

Which component is added to a test circuit to give a continuously variable potential difference across the component being tested, and how is it connected?

A variable resistor (rheostat), connected in series with the component.

What are the steps to investigate how the resistance of a thermistor varies with temperature?

e.g. using a water bath from $20\,^{\circ}\mathrm{C}$ to $80\,^{\circ}\mathrm{C}$

1. Connect the thermistor in series with a cell and ammeter, with a voltmeter across it.
2. Place it in the water bath and record $V$, $I$ and temperature every $10\,^{\circ}\mathrm{C}$.
3. Calculate $R = V \div I$ at each temperature and plot resistance against temperature.

In a test circuit, how do you show that a diode conducts in one direction only?

Reverse the diode (or the supply connections) and take readings again — the current is about zero in reverse.