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Question : 4
Total: 6
SECTION -C
(a) State the underlying principle of a moving coil galvanometer.
(b) Give two reasons to explain why a galvanometer cannot as such be used to measure the value of the current in a given circuit.
(c) Define the terms: (i) voltage sensitivity and (ii) current sensitivity of a galvanometer.
Solution:
(a) Principle
(b) Two reasons
(c) Definitions of voltage sensitivity and current sensitivity
(a) 'A current carrying coil can experience a torque in a magnetic field.'
(b) (i) Galvanometer is a very sensitive device, it gives a full scale deflection for a current of the order of a fewµ A
(ii) Resistance of galvanometer is not very small, hence it will change the value of current in the circuit branch when connected (in series in that branch).
(c) Current sensitivity is defined as the deflection per unit current.
(Alternatively, current sensitivity=
Voltage sensitivity is defined as the deflection per unit potential difference applied.
(Alternatively, Voltage sensitivity=
(b) Two reasons
(c) Definitions of voltage sensitivity and current sensitivity
(a) 'A current carrying coil can experience a torque in a magnetic field.'
(b) (i) Galvanometer is a very sensitive device, it gives a full scale deflection for a current of the order of a few
(ii) Resistance of galvanometer is not very small, hence it will change the value of current in the circuit branch when connected (in series in that branch).
(c) Current sensitivity is defined as the deflection per unit current.
(Alternatively, current sensitivity
Voltage sensitivity is defined as the deflection per unit potential difference applied.
(Alternatively, Voltage sensitivity
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