Advertisements
Advertisements
Question
Why does a galvanometer show a momentary deflection at the time of charging or discharging a capacitor? Write the necessary expression to explain this observation.
Advertisements
Solution
As the capacitor is connected to the battery, the electrons start moving towards the plate connected to the negative terminal of the battery and electrons leave from the plate connected to the positive terminal of the battery. This happens until the potential of the capacitor becomes equal to that of the battery. As this happens very quickly, the charging current produces a deflection. The reverse process is repeated for discharging that is the charge is lost. As the galvanometer can be considered as a resistance, the circuit behaves like a R-C circuit having time constant equal to RC. Hence the expression governing this phenomenon is
`q=q_0(1-e^(-t/(RC)))`
APPEARS IN
RELATED QUESTIONS
Show that the current flowing through a moving coil galvanometer is directly proportional to the angle of deflection of coil.
State the underlying principle of working of a moving coil galvanometer. Write two reasons why a galvanometer can not be used as such to measure current in a given circuit. Name any two factors on which the current sensitivity of a galvanometer depends.
A galvanometer coil has a resistance of 12 Ω and the metre shows full scale deflection for a current of 3 mA. How will you convert the metre into a voltmeter of range 0 to 18 V?
The AC voltage across a resistance can be measured using a ______.
The current sensitivity of a galvanometer is defined as ______.
A moving coil galvanometer can be converted into an ammeter by ______.
The coil of galvanometer consists of 100 turns and effective area of 1 square cm. The restoring couple is 10-8 N-m/rad. The magnetic field between the pole pieces is 5T. The current sensitivity of this galvanometer will be ______.
A resistance of 3Ω is connected in parallel to a galvanometer of resistance 297Ω. Find the fraction of current passing through the galvanometer.
A voltmeter has a range of 0 - 20 V and a resistance of 500 Q. Explain how can be used to measure voltages from 0 - 200 volt?
