Moving Charges and Magnetism

Consider a moving coil galvanometer (MCG): Choose the correct answer from the options given below:

1. A, D Only
2. A, B Only
3. A, B, E Only
4. B, D, E Only

A galvanometer having a coil of resistance 30 need 20 mA of current for full-scale deflection. If a maximum current of 3 A is to be measured using this galvanometer, the resistance of the shunt to be added to the galvanometer should be 30X , where X is

1. 447
2. 298
3. 149
4. 596

An electron projected perpendicular to a uniform magnetic field B moves in a circle. If Bohr's quantization is applicable, then the radius of the electronic orbit in the first excited state is :

1. h eB
2. 4h eB
3. h2 eB
4. 2h eB

A galvanometer has a coil of resistance 200 with a full scale deflection at 20 . The value of resistance to be added to use it as an ammeter of range (0 - 20) mA is :

1. 0.40
2. 0.10
3. 0.20
4. 0.50

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

1. Both Statement I and Statement II are false
2. Statement I is false but Statement II is true
3. Both Statement I and Statement II are true
4. Statement I is true but Statement II is false

A proton and a deuteron (q = +e, m = 2.0 u) having same kinetic energies enter a region of uniform magnetic field B, moving perpendicular to B. The ratio of the radius rd of deuteron path to the radius rp of the proton path is:

1. 1 : 2
2. 1 : 1
3. 2 : 1
4. 1 : 2

A long straight wire of radius a carries a steady current I. The current is uniformly distributed across its cross section. The ratio of the magnetic field at a2 and 2a from axis of the wire is :

1. 4 : 1
2. 3 : 4
3. 1 : 1
4. 1 : 4

An element l = x i is placed at the origin and carries a large current I = 10 A. The magnetic field on the y-axis at a distance of 0.5 m from the element x of 1 cm length is: [figure]

1. 10 10-8 T
2. 8 10-8 T
3. 4 10-8 T
4. 12 10-8 T

In a co-axial straight cable, the central conductor and the outer conductor carry equal currents in opposite directions. The magnetic field is zero :

1. inside the outer conductor
2. outside the cable
3. in between the two conductors
4. inside the inner conductor

A galvanometer of resistance 100 when connected in series with 400 measures a voltage of upto 10 V. The value of resistance required to convert the galvanometer into ammeter to read upto 10 A is x 10-2 . The value of x is :

1. 2
2. 20
3. 800
4. 200

The electrostatic force ( F1 ) and magnetic force ( F2 ) acting on a charge q moving with velocity v can be written :

1. F1 = q B, F2 = q( B v)
2. F1 = q V E, F2 = q( B V)
3. F1 = q E, F2 = q( V B)
4. F1 = q E, F2 = q( B V)

An electron is projected with uniform velocity along the axis inside a current carrying long solenoid. Then :

1. the electron will experience a force at 45 to the axis and execute a helical path.
2. the electron will be accelerated along the axis.
3. the electron path will be circular about the axis.
4. the electron will continue to move with uniform velocity along the axis of the solenoid.

A galvanometer has a resistance of 50 and it allows maximum current of 5 mA. It can be converted into voltmeter to measure up to 100 V by connecting in series a resistor of resistance :

1. 19500
2. 5975
3. 20050
4. 19950

In an ammeter, 5\% of the main current passes through the galvanometer. If resistance of the galvanometer is G, the resistance of ammeter will be :

1. G200
2. G199
3. 199 G
4. 200 G

A rigid wire consists of a semicircular portion of radius R and two straight sections. The wire is partially immersed in a perpendicular magnetic field B=B0 k as shown in figure. The magnetic force on the wire if it has a current i is: [figure]

1. iBR j
2. -2iBR j
3. 2iBR j
4. -iBR j

A uniform magnetic field of 2 10-3 T acts along positive Y-direction. A rectangular loop of sides 20 cm and 10 cm with current of 5 A is in Y-Z plane. The current is in anticlockwise sense with reference to negative X axis. Magnitude and direction of the torque is:

1. 2 10-4 N-m along negative Z-direction
2. 2 10-4 N-m along positive X-direction
3. 2 10-4 N-m along positive Y-direction
4. 2 10-4 N-m along positive Z-direction

Two insulated circular loops A and B of radius 'a' carrying a current of 'I' in the anti clockwise direction as shown in the figure. The magnitude of the magnetic induction at the centre will be : [figure]

1. 2 0 Ia
2. 0 I 2a
3. 0I2a
4. 2 0 Ia

The deflection in moving coil galvanometer falls from 25 divisions to 5 divisions when a shunt of 24 is applied. The resistance of galvanometer coil will be :

1. 48
2. 100
3. 96
4. 12

A galvanometer having coil resistance 10 shows a full scale deflection for a current of 3 mA. For it to measure a current of 8 A, the value of the shunt should be:

1. 3.75 10-3
2. 3 10-3
3. 4.85 10-3
4. 2.75 10-3

Two particles X and Y having equal charges are being accelerated through the same potential difference. Thereafter they enter normally in a region of uniform magnetic field and describe circular paths of radii R1 and R2 respectively. The mass ratio of X and Y is :

1. ( R1R2 )
2. ( R2R1 )
3. ( R2R1 )2
4. ( R1R2 )2

A proton moving with a constant velocity passes through a region of space without any change in its velocity. If E and B represent the electric and magnetic fields respectively, then the region of space may have : Choose the most appropriate answer from the options given below :

1. (A), (B) and (C) only
2. (A), (C) and (D) only
3. (A), (B) and (D) only
4. (B), (C) and (D) only

A current of 200 deflects the coil of a moving coil galvanometer through 60 . The current to cause deflection through 10 radian is :

1. 120
2. 180
3. 30
4. 60