Question 500: Current Electricity

Question

Two identical galvanometers are converted into voltmeter and millivoltmeter. As compared to the series resistance of voltmeter, the series resistance of millivoltmeter will be

Accepted Answer

To understand the answer, let's consider how a galvanometer is converted into a voltmeter.
The conversion is done by adding a series resistor so that when the maximum voltage, $$V_{max}$$, is applied, the current through the galvanometer (which has a full-scale deflection current $$I_g$$) is not exceeded.
The relation used is:
$$R_{series} = \frac{V_{max}}{I_g} - R_g,$$
where $$R_g$$ is the galvanometer's internal resistance.
For a voltmeter, $$V_{max}$$ is relatively high. Therefore, its series resistance becomes larger.
For a millivoltmeter, $$V_{max}$$ is much smaller, resulting in a smaller series resistance.
Thus, compared to the voltmeter, the series resistance of the millivoltmeter is $$	extbf{less}$$.
The correct answer is Option C.

Answer

equal

Answer

more

Answer

less

Answer

zero

Current Electricity

Two identical galvanometers are converted into voltmeter and millivoltmeter. As compared to the series resistance of voltmeter, the series resistance of millivoltmeter will be

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