moving charges and magnetism Questions

Magnetic flux (in weber) in a closed circuit of resistance 20 Ω varies with time t(s) as φ = 8t² − 9t + 5. The magnitude of the induced current at t = 0.25 sec will be ____ mA.

An infinite current carrying wire is bent as shown in Figure Then magnetic field at O, is

Two concentric coplanar circular loops of radii a and b carry currents x and y respectively in opposite directions (one clockwise and the other anticlockwise). magnitude of net magnetic field at the centre of the loops is half of that due to x alone

A coil of 40 turns and area 4 cm2 is suddenly removed from a magnetic field, it is observed that a charge of 2×10−4 C flows into the coil, if resistance of the coil is 80Ω, the magnetic flux density in Wb m−2 is :

A loop PQR carries a current i = 2 A as shown in the figure. A uniform magnetic field B = 2T exists in space parallel to the plane of the loop. The magnetic torque on the loop is

A particle of charge -16 × 10-18 C moving with velocity 10 ms-1 along the x−axis enters in a region where a magnetic field of induction B is along the y−axis and an electric field of magnitude 104 V/m is along the negative z−axis. If the charged part

A particle of mass m and charge q has velocity if an electric field and magnetic field act on the particle , its speed will double after a time :

A negative charge is coming towards the observer. The direction of the magnetic field produced by it will be (as seen by observer):