Before starting the experiments, the following things should be checked:
	<ul><li>The coarse variable resistance R<sub>1</sub> for ammeter calibration should be rated for full supply voltage (e.g., 110 V D.C). Moreover, its current rating should be adequate to cover the full scale value of the test ammeter (e.g., 5A D.C).</li>
	<li>The fine-variable rheostat R<sub>2</sub> should be of relatively low resistance but of current rating adequate of passing full scale current of the test ammeter.</li> 
	<li>The potential divider R should be suitable for full supply voltage (e.g., 110 V D.C) and of adequate current rating (say, 5A).</li>
	<li>The full supply voltage should be greater than the full scale reading of the test voltmeter.</li></ul>