A straight horizontal conducting rod of length 0.45m and mass 60g is suspended by two vertical wires at its ends.  A current of 5.0 A is set up in the rod though the wires.
(a) What magnetic field should be set up normal to the conductor in order that the tension in the wires is zero?
(b) What will be the total tension in the wires if the direction of current is reversed keeping the magnetic field same as before? (Ignore the mass of the wires.) g = 9.8 ms^-2.

How are materials classified according to their behaviour in magnetic field?

Discuss the sensitivity of a moving coil galvanometer.

Find the expression for maximum energy of a charged particle accelerated by a cyclotron.

Explain using a labelled diagram, the principle and working of a moving coil galvanometer. What is the function of
(i) uniform radial magnetic field
(ii) soft iron core?
Also, define the terms
(iii) current sensitivity and
(iv) voltage sensitivity of a galvanometer.
Why does increasing the current sensitivity not necessarily increase voltage sensitivity?

(i) Using Ampere's circuital law, derive the expression for the magnetic field in the vector from at a point on the axis of solenoid.
(ii) What does a toroid consist of? Find out the expression for the magnetic field inside a toroid for N turns of the coil having the average radius r and carrying a current I.Show that the magnetic field in the open space interior and exterior to the toroid is zero.

A monoenergetic(18kev) electron beam initially in the horizontal direction is subjected to a horizontal magnetic field of 0.4 passes normal to the initial direction.Estimate the up or down deflection of the beam over a distance of 30 cm.
\((mc=9.11\times 10-19C).\)

(a) Draw a labelled diagram of a moving coil galvanometer. Describe briefly its principle and working. 
(b) Answer the following:
(i) Why is it necessary to introduce a cylindrical soft iron core inside the coil of a galvanometer?
(ii) Increasing the current sensitivity of a galvanometer may not necessarily increase its voltage sensitivity. Explain, giving reason.

(i) Draw a schematic sketch of a cyclotron. Explain clearly the role of crossed electric and magnetic field in accelerating the charge. Hence, derive the expression for the kinetic energy acquired by the particles.

An element  Δl = Δx \(\hat i\) is placed at the origin and carries a large current I = 10 A (Figure). What is the magnetic field on the y-axis at a distance of 0.5 m. Δ x = 1 cm.