Magnetism Question 104
Question: Two tangent galvanometers having coils of the same radius are connected in series. A current flowing in them produces deflections of 60° and 45° respectively. The ratio of the number of turns in the coils is
[MP PET 1995; MP PMT 1999]
Options:
A) 4/3
B) $ (\sqrt{3}+1)/1 $
C) $ (\sqrt{3}+1)/(\sqrt{3}-1) $
D) $ \sqrt{3}/1 $
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Answer:
Correct Answer: D
Solution:
In the first galvanometer $ i _{1}=K _{1}\tan {\theta _{1}}=K _{1}\tan 60^{o}=K _{1}\sqrt{3} $ In the second galvanometer $ i _{2}=K _{2}\tan {\theta _{2}}=K _{2}\tan 45^{o}=K _{2} $ In series i1 = i2
Therefore $ K _{1}\sqrt{3}=K _{2}\Rightarrow \frac{K _{1}}{K _{2}}=\frac{1}{\sqrt{3}} $ But $ K\propto \frac{1}{n}\Rightarrow $
$ \frac{K _{1}}{K _{2}}=\frac{n _{2}}{n _{1}} $ \ $ \frac{n _{1}}{n _{2}}=\frac{\sqrt{3}}{1} $ .
BETA
