Current Electricity 4 Question 6
6. The galvanometer deflection, when key is closed but is open equals (see figure). On closing also and adjusting to , the deflection in galvanometer becomes . The resistance of the galvanometer is given by (neglect the internal resistance of battery) :
(Main 2019, 12 Jan I)
(a)
(b)
(c)
(d)
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Solution:
- For a galvanometer,
or
where,
and
Now,
where,
Hence, galvanometer current is
i.e.,
where,
As deflection is given
When both keys
Current through galvanometer will be
Now, dividing Eq. (i) by Eq. (ii), we get
Substituting
we get