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Question : 29
Total: 35
(a) Briefly describe how the current sensitivity of a moving coil galvanometer can be increased.
(b) A galvanometer shows full scale deflection for currentI g R 1 ( 0 − V ) R 2 ( 0 − 2 V )
(b) A galvanometer shows full scale deflection for current
Solution: 👈: Video Solution
(a) Current sensitivity of galvanometer:
Current sensitivity of galvanometer= θ ∕ I = N B A ∕ c
So, to increase the current sensitivity:
(i) Permanent magnet should be strong so thatB
(ii)N A
(iii) Value ofc
(b) To convert into a voltmeter of range( 0 − V )
V = I g ( R g + R 1 )
To convert into a voltmeter of range( 0 − 2 V )
2 V = I g ( R g + R 2 )
Dividing equation (i) by (ii)
= ( R g + R 1 ) ∕ ( R g + R 2 )
Or,
= ( R g + R 1 ) ∕ ( R g + R 2 )
∴ R g = R 2 − 2 R 1
Current sensitivity of galvanometer
So, to increase the current sensitivity:
(i) Permanent magnet should be strong so that
(ii)
(iii) Value of
(b) To convert into a voltmeter of range
To convert into a voltmeter of range
Dividing equation (i) by (ii)
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