EASY
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Given below are two statements:

Statement I: If the number of turns in the coil of a moving coil galvanometer is doubled then the current sensitivity becomes double.

Statement II: Increasing current sensitivity of a moving coil galvanometer by only increasing the number of turns in the coil will also increase its voltage sensitivity in the same ratio

In the light of the above statements, choose the correct answer from the options given below:

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Important Questions on Moving Charges and Magnetism

MEDIUM
For a moving coil galvanometer, the deflection in the coil is 0.05 rad when a current of 10 mA is passed through it. If the torsional constant of suspension wire is 4.0 × 105 N m rad-1, the magnetic field is 0.01 T and the number of turns in the coil is 200, the area of each turn (in cm2 ) is :
MEDIUM

Directions: Each of the following sentences in this section has a blank space and four words or group of words given after the sentence. Select the word or group of words you consider most appropriate for the blank space and indicate your response on the Answer Sheet accordingly.

Every rash driver becomes a ____ killer.

EASY
The number of turns of the coil of a moving coil galvanometer is increased in order to increase current sensitivity by 50%. The percentage change in voltage sensitivity of the galvanometer will be :
MEDIUM
The current sensitivity of a moving coil galvanometer depends on,
MEDIUM
The deflection in a moving coil galvanometer is reduced to half when it is shunted with X Ω coil. The relation between X and resistance of galvanometer G is
MEDIUM
Current sensitivity of a moving coil galvanometer is 5 div/mA and its voltage sensitivity (angular deflection per unit voltage applied) is 20 div/V. The resistance of the galvanometer is
HARD
A rectangular coil of120 turns and an area of 10×10-4m2 is suspended in a radial magnetic field of 45×19-4 T. If a current of 2 mA through the coil gives it a deflection of 36°. Find the effective torsion constant for the spring system holding the coil.
MEDIUM
A galvanometer, whose resistance is 50 ohm , has 25 divisions in it. When a current of 4×10-4 A passes through it, its needle (pointer) deflects by one division. To use this galvanometer as a voltmeter of range 2.5 V it should be connected to a resistance of:
EASY

Two sentences are given below and you are required to find the correct sentence which combines both the sentences.

Which is the correct combination of the given two sentences?

He is too tired. He could not stand.

MEDIUM
A coil in the shape of an equilateral triangle of side 10 cm lies in a vertical plane between the pole pieces of permanent magnet producing a horizontal magnetic field 20mT. The torque acting on the coil when a current of 0.2 A is passed through it and its plane becomes parallel to the magnetic field will be x×10-5Nm. The value of x is
MEDIUM

In the following sentence, a blank space with four options is given. Select whichever preposition or determiner you consider the most appropriate for the blank space.

These are the good rules to live _____.

EASY
The number of turns in a coil of Galvanometer is tripled, then
MEDIUM
A millivoltmeter of 25 mV range is to be converted into an ammeter of 25 A range. The value (in ohm) of necessary shunt will be
EASY
The current sensitivity of moving coil galvanometer is increased by 25%. This increase is achieved only changing in the number of turns of coils and area of cross section of the wire while keeping the resistance of galvanometer coil constant. The percentage change in the voltage sensitivity will be:
MEDIUM

The galvanometer deflection, when key K1 is closed but K2 is open, equals θ0 (see figure). On closing K2 also and adjusting R2 to 5Ω, the deflection in galvanometer becomes θ05. The resistance of the galvanometer is, then, given by [Neglect the internal resistance of battery]:

Question Image

EASY
A circuit contains an ammeter, a battery of 30 v and a resistance 40.8 ohm all connected in series. If the ammeter has coil of resistance 480 ohm and a shunt of 20 ohm, the reading in the ammeter will be:
HARD
A moving coil galvanometer has 50 turns and each turn has an area 2×10-4 m2 . The magnetic field produced by the magnet inside the galvanometer is 0.02 T . The torsional constant of the suspension wire is 10-4 N m rad-1 . When a current flows through the galvanometer, a full scale deflection occurs if the coil rotates by 0.2 rad . The resistance of the coil of the galvanometer is 50 Ω . This galvanometer is to be converted into an ammeter capable of measuring current in the range 0-1.0 A . For this purpose, a shunt resistance is to be added in parallel to the galvanometer. The value of this shunt resistance, in ohms, is α. Write the value of α, where   is the greatest integer function.
EASY
The resistance of the required shunt in order to pass 10% of the main current in a galvanometer of 99Ω resistance should be
EASY
To increase the current sensitivity of a moving coil galvanometer by 50 %, its resistance is increased, so that new resistance becomes twice its initial resistance, by what factor does its voltage sensitivity change?
HARD
Consider two identical galvanometers and two identical resistors with resistance R. If the internal resistance of the galvanometers Rc<R2, which of the following statement(s) about any one of the galvanometers is(are) true ?