Magnetism and M...

Charge Q is uniformly distributed on a thin insulating ring of mass m which is initially at rest. To what angular velocity will the ring be accelerated when a magnetic field B, perpendicular to the plane of the ring, is switched on?

A standing wave $$y=2A \sin kx \cos \omega t$$ is set up in the wire AB fixed at both the ends by two vertical walls . The region between the walls contains a constant magnetic field B. Now, answer the following question.

The wire is found to vibrate in the third harmonic. The maximum emf induced is

A standing wave $$y=2A sin kx cos \omega t$$ is set up in the wire AB fixed at both the ends by two vertical walls . The region between the walls contains a constant magnetic field B. Now, answer the following question.

In which of the following modes the emf induced in AB is always zero?

Consider two parallel, conducting frictionless tracks kept in a gravity-free space as shown in fig. A movable conductor PQ initially kept at OA, is given a velocity $$10 m s^{-1}$$ towards the right. Space contains a magnetic field which depends upon the distance moved by conductor PQ from the OA line and given by $$\vec { B } =cx (-\hat {k}) $$[c=constant =1 S.I unit] the mass of the conductor PQ is  1 kg length of PQ is 1 m. Answer the following question based on the above passage.

The distance traveled by the conductor when its speed is 5 m/s is 

Consider two parallel, conducting frictionless tracks kept in a gravity-free space as shown in fig. A movable conductor PQ, initially kept at OA, is given a velocity $$10 m s^{-1}$$ towards right. The space contains a magnetic field which depends upon the distance moved by conductor PQ from the OA line and given by $$\vec { B } =cx (-\hat {k}) $$[c=constant =1 S.I unit] the mass of the  conductor PQ is  1 kg length of PQ is 1 m. Answer the following question based on the above passage.

The work done by magnetic force acting on the conductor PQ during its motion in the time interval t=0 to t=t seconds when the speed of conductor is $$5 m\, s^{-1} $$ is 

A metal rod of resistance $$ 20 \Omega $$ is fixed along a diameter of a conducting ring of radius 0.1 m and lies on x-y plane. There is a magnetic field $$ \overrightarrow {B  }=(50T) \hat k$$. the ring rotated with angular velocity $$\omega=20 rad/s$$ about its axis. An external resistance of $$ 10 \Omega $$ is connected across the centre of the ring and rim. The current through external resistance is 

The radius of the circular conducting loop shown in fig. is R. Magnetic field is decreasing at a constant rate $$\alpha$$ Resistance per unit length of the loop is $$\rho$$then the current in wire AB is (AB is one of the diameter)

A solenoid has an inductance of $$60$$ henrys and a resistance of $$30$$ ohms. If it is connected to a $$100$$ volt battery, how long will it take for the current to reach $$\dfrac{e - 1}{e} \approx 63.2\%$$ of its final value

A small coil C with $$ N = 200 $$ turns is mounted on one end of a balance beam and introduced between the poles of an electromagnet  as shown in figure. The cross sectional area of coil is $$A= 1.0 cm$$  length of arm OA of the balance beam is  $$I=30 cm.$$
When there is no current in the coil the balance is in equilibrium. On passing a current $$ I = 22 mA $$ through the coil the equilibrium is restored by putting the additional counter weight of mass $$ \theta m = 60 mg $$ on the balance pan. Find the magnetic induction at the spot where coil is located.

The magnetic field in the cylindrical region shown in figure increases at a constant rate of $$20\, mT/sec.$$ Each side of the square loop $$ABCD$$ has a length of $$1 \,cm$$ and resistance of $$4\Omega$$. Find the current in the wire AB if the switch S is closed