A beam of cathode rays is subjected to cross Electric (E) and magnetic fields(B). The fields are adjusted such that the beam is not deflected. The specific charge of the cathode rays is given by:

1. $\frac{B^2}{2V{E}^2}$

2. $\frac{2V{B}^2}{E^2}$

3. $\frac{\mathrm{2V}{E}^2}{B^2}$

4. $\frac{E^2}{2V{B}^2}$

(where V is the potential difference between cathode and anode)

Under the influence of a uniform magnetic field, a charged particle moves with constant speed \(v\) in a circle of radius \(R.\) The time period of rotation of the particle:

A closed-loop \(PQRS\) carrying a current is placed in a uniform magnetic field. If the magnetic forces on segments \(PS,\) \(SR,\) and \(RQ\) are \(F_1, F_2~\text{and}~F_3\) respectively, and are in the plane of the paper and along the directions shown, then which of the following forces acts on the segment \(QP?\)
        

1. \(F_{3} - F_{1} - F_{2}\)

2. \(\sqrt{\left(F_{3} - F_{1}\right)^{2} + F_{2}^{2}}\)

3. \(\sqrt{\left(F_{3} - F_{1}\right)^{2} - F_{2}^{2}}\)

4. \(F_{3} - F_{1} + F_{2}\)

A particle of mass \(m,\) charge \(Q,\) and kinetic energy \(T\) enters a transverse uniform magnetic field of induction \(\vec B.\) What will be the kinetic energy of the particle after seconds?

The resistance of an ammeter is 13 Ω and its scale is graduated for a current up to 100 A. After an additional shunt has been connected to this ammeter, it becomes possible to measure currents up to 750 A by this ammeter. The value of shunt resistance is:

1. 20 $\Omega$

2. 2 $\Omega$

3. 0.2 $\Omega$

4. 2 k$\Omega$