Question

In an ammeter 4% of the mains current is passing through galvanometer. If the galvanometer is shunted with a 3 ohm resistance

Answer 1

Answer:

117 ohm s= ig÷i-ig)×g use this formula where ig=current in galvanometer g=resistance in galvanometer s=shunt resistance i= current in shunt

Answer 2

The resistance of the galvanometer is 72 ohm.

Given,

In an ammeter 4% of the mains current is passing through galvanometer ;

shunted with a 3 ohm resistance

Find,

Find the resistance of the galvanometer

Solution,

• With the galvanometer or ammeter, a shunt is a low resistance device linked in parallel.
• A galvanometer or an ammeter should not be placed directly in a circuit if the current running through it is strong since doing so could destroy the instrument.
• This instrument is connected in parallel with one that has a low resistance, or a shunt, to get around this problem. The current then mostly travels through this low resistance (also known as a shunt) and barely any current actually goes through the instrument. Galvanometers and ammeters are safe as a result of it.

Shunt is given, $S = \frac{I_{g}*G }{I- I_{g} }$

where, $I_{g}$ be the current across galvanometer

and, Potential difference across G

=> $3 = \frac{\frac{4}{100} * IG}{I- \frac{4}{100} I}$

=> $3 = \frac{4G}{96}$

=> $G= \frac{3*96}{4}$

=> G = 72 ohm

Hence, the resistance of the galvanometer is 72 ohm.

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