A current element 3 dl is at (0,0,0) along y-axis. if dl =1 cm, find the magnetic field at a distance 20 cm on the x-axis.

5

(a)

A wire of radius 0.8 cm carries a current of 100 A which is uniformly distributed over its cross-section. Find the magnetic field (a) at 0.2 cm from the axis of the wire (b) at the surface of the wire and (c) at a point outside the wire 0.4 cm from the surface of the wire. Neglect the permeability of the material of wire.

5

(a)

A solenoid of length 0.5 m has a radius of 1 cm and is made up of 500 turns. It carries a current of 5 A. What is the magnitude of the magnetic field inside the solenoid ?

5

(a)

A proton enters a magnetic field of flux density 2.5 T with a speed of 1.5 x 10⁷ ms^-1 at an angle of 30^o with the field. Find the force on the proton.

5

(a)

An electron of energy 2000 eV describes a circular path in magnetic field of flux density 0.2 T. What is the radius of the path ? take e = 1.6 x 10^-19 C, m = 9 x 10 ^-31 kg.

5

(a)

A straight wire of mass 200 g and length 1.5 m carries a current of 2 A. It is suspended in mid air by a uniform horizontal magnetic field B . What is the magnitude of the magnetic field?

5

(a)

A long straight conductor C carrying a current of 3 A is placed parallel to a short conductor D of length 5 cm, carrying a current 4 A. The two conductors are 10 cm apart. Find
(i) the magnetic field due to C at D.
(ii) The approximate force on D.

5

(a)

Calculate the force per unit length on a long straight wire carrying current 4 A due to parallel wire carrying 6 A current. if the distance between the wires is 3 cm.

5

(a)

When a galvanometer having 30 divisions scale and 100 \(\Omega \) resistance is connected in series with the battery of e.m.f. 3 volt through a resistance of 200 \(\Omega \)  , it shows full scale deflection. Find the fogure of merit of the galvanometer in microampere.

5

(a)