Moving Charges and Magnetism

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 proton is moving undeflected in a region of crossed electric and magnetic fields at a constant speed of 2 105 m s-1. When the electric field is switched off, the proton moves along a circular path of radius 2 cm . The magnitude of electric field is x 104 N/C. The value of x is . Take the mass of the proton =1.6 10-27 kg.

Two long parallel wires X and Y, separated by a distance of 6 cm , carry currents of 5 A and 4A, respectively, in opposite directions as shown in the figure. Magnitude of the resultant magnetic field at point P at a distance of 4 cm from wire Y is x 10-5 T. The value of x is . Take permeability of free space as 0=4 10-7 SI units. [figure]

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 square loop of edge length 2 m carrying current of 2 A is placed with its edges parallel to the x-y axis. A magnetic field is passing through the x-y plane and expressed as B = B0(1 + 4x) k, where B0 = 5 T. The net magnetic force experienced by the loop is N.

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

An electron with kinetic energy 5 eV enters a region of uniform magnetic field of 3 perpendicular to its direction. An electric field E is applied perpendicular to the direction of velocity and magnetic field. The value of E, so that electron moves along the same path, is N C-1. (Given, mass of electron = 9 10-31 kg, electric charge = 1.6 10-19 C)

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

Match List I with List II Choose the correct answer from the options given below:

1. A-I, B-III, C-II, D-IV
2. A-IV, B-II, C-III, D-I
3. A-III, B-I, C-II, D-IV
4. A-IV, B-III, C-II, D-I