Magnetic Effect...

A uniform magnetic field B is directed out of the page. A metallic wire has the shape of a square frame and is placed in the field as shown. While the shape of the wire is steadily transformed into a circle in the same plane, the current in the frame:

The current I in the straight conductor varies sinusoidally with time as shown. (A positive value of I is in the direction indicated). At time t₁ the induced current in the rectangular loop is clockwise. What is the current in the rectangular loop at time t₂ and time t₃ respectively?

A charge +2q moves vertically upwards with speed v, a second charge − q moves horizontally to the right with the same speed v, and a third charge +q moves horizontally to the right with the same speed v. The point P is located a perpendicular distance a away from each charge as shown in the figure. The magnetic field at point P is

For the solenoids shown in the diagram (which are assumed to be close to each other), the resistance of the left-hand circuit is slowly increased. In which direction does the current flow through galvanometer in the right-hand circuit?

The wire shown in figure carries a current of 60A. Determine the magnitude of the magnetic field at the centre O. Given radius of the bent coil is 2 cm.

A circular loop of radius R = 20 cm is placed in a uniform magnetic field  in x-y plane as shown. The loop carries a current i = 1A in the direction as shown in the figure. The torque acting on the loop is

Shown in the figure is a conductor carrying a current I. The magnetic field intensity at the point O(common centre of all the three arcs) is :

Consider a toroid of circular cross-section of radius b, major radius R much greater than minor radius b, (see diagram) find the total energy stored in magnetic field of toroid –

Two circular coils made of similar wires but of radius 20 cm and 40 cm are connected in parallel. The ratio of magnetic fields at their centre is -

Two coaxial solenoids are made by winding thin insulated wire over a pipe of cross-sectional area A = 10 cm² and length l = 20 cm. If one of the solenoids has 300 turns and the other 400 turns, their mutual-inductance is