1) The length of VW, WX, XY and YZ are 10.0 cm each. Find the net force on the segment of wire, VWXYZ, in the figure below if the strength of the magnetic field B is 0.40 T and the current I flowing through the wire is 5.0 A.

2) A current balance is used to measure the strength of the magnetic field B of an electromagnet. The side PQ of a current balance is inserted inside a large electromagnet. The direction of magnetic field is as shown in the figure below.

Length of PQ is L. PQ and RS are d₁ and d₂ respectively from the pivot. A load of mass m is placed alongside RS. Take acceleration due to gravity to be g.

What is the direction and magnitude of the current along PQ?

3) A charge Q is travelling with speed v in a magnetic field B. At one instant in time, its velocity is at an angle θ to the horizontal as shown.

What is the magnetic force acting on it at this instant in time?

4) The diagram shows an electron beam entering the region between two metal plates in which there are uniform electric and magnetic fields.

If the speed of the electrons in the beam is 6.00 × 105 m s⁻¹, and the strength of the magnetic field is 0.238 mT, what is the magnitude and direction of the electric field that will allow the beam to pass through undeflected?

5) P and Q are two ions with masses m_P and m_Q respectively. They have the same charge q and the work done on both charges after passing through an applied p.d. of V is qV. Subsequently, P and Q enter a magnetic field B.

The radius of the path of ions P and Q is r_P and r_Q respectively. What is the ratio of r_Q / r_P?