Question

What is the sensitivity of the galvanometer (that is, what current gives a full-scale deflection) inside a voltmeter that has a 25.0-kΩ resistance on its 100-V scale?

a) 4.0 mA
b) 5.0 mA
c) 6.0 mA
d) 7.0 mA

Answer 1

The sensitivity of the galvanometer inside a voltmeter with a 25.0 kΩ resistance and a 100-V scale is 4.0 mA, which is the current that would cause a full-scale deflection.

Step-by-step explanation:

The sensitivity of the galvanometer inside a voltmeter is determined by the current that causes a full-scale deflection when the maximum voltage of the scale is reached. The sensitivity of the galvanometer inside a voltmeter with a 25.0 kΩ resistance and a 100-V scale is 4.0 mA, which is the current that would cause a full-scale deflection.

For a voltmeter with a 25.0-kΩ resistance on its 100-V scale, the full-scale current can be calculated using Ohm's Law, which states that current (I) equals voltage (V) divided by resistance (R). In this case, the maximum voltage is 100 V and the resistance is 25.0 kΩ (or 25,000 Ω), so the current that would give a full-scale deflection is I = V/R, which is 100 V / 25,000 Ω = 0.004 A, or 4.0 mA.