With a voltmeter, the internal resistance of which is 1000 Ohm and which is designed for a limiting

With a voltmeter, the internal resistance of which is 1000 Ohm and which is designed for a limiting voltage of 150 V, it is necessary to measure a voltage 6 times greater: 900 V. What resistor will have to be connected in series with the voltmeter in order to take measurements?

To find the required resistance of the connected resistor, we will use the formula: Rc = Rv * Uc / Uv = Rv * (U – Uv) / Uv.

Variables: Rv – internal resistance of the taken voltmeter (Rv = 1000 Ohm); U is the measured voltage (U = 900 V); Uv – limit voltage (Uv = 150 V).

Let’s calculate: Rc = Rv * (U – Uv) / Uv = 1000 * (900 – 150) / 150 = 5000 Ohm.

Answer: To make a measurement, you need to connect a 5 kΩ resistor.