galvanometer into a voltmeter?

Question

To convert a galvanometer into a voltmeter, the galvanometer must be connected in series with a large resistor (called a multiplier). What are the reason(s) for using a large resistance for the multiplier? I've tried getting the info from my book, but I am just not understanding what they mean. Could someone simplify please?

Answer 1

The galvanometer measures current, not voltage. BUT Ohms law can be used to convert a current to a voltage:

V = I * R

V is the voltage, I is the current, R is a resistance

Multiplying a resistance by a current is why the resistor is called a current multiplier.

You need to know what the maximum current (maximum needle deflection) rating for the galvanometer is (also called the "full scale" current). Typically a sensitive galvanometer has a maximum current of 50 microAmps. If the needle is normally in the middle, then the full scale reading will be both ways, positive and negative.

Example: To measure 10 Volts full-scale with a 50 uA meter, you need a 200,000 Ohm resistor in series with the meter.

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Answer 2

Super Hero is here to save the situation & answer ur question
:D

Multiplier:
Its a very large resistance that connected in series to the galvanometer, Why ??

a) To increase the total resistance of the instrument, becouse the potintial difference across the galvanometer is extremely small even when a large scale deflection occurs
b) To draw negligible amount of the current, so the potintial difference being measured stay nearly unchanged
c) To make the instrument suitable to measure high potintial differences

These r the main 3 reasons for using a large resistance for a multiplier

Answer 3

galvanometer could be switched over to voltmeter via connecting a resistance in sequence. So, R = V/(ig - Rg) the place R is the resistance and Rg is resistance of Galvanometer; n is the ratio of skill differences.