If a square loop \(\text{ABCD}\) carrying a current \(i\) is placed near and coplanar with a long straight conductor \(\mathrm{XY}\) carrying a current \(I\), what will be the net force on the loop?
               
1. \(\frac{\mu_0Ii}{2\pi}\)
2. \(\frac{2\mu_0IiL}{3\pi}\)
3. \(\frac{\mu_0IiL}{2\pi}\)
4. \(\frac{2\mu_0Ii}{3\pi}\)

A circuit contains an ammeter, a battery of \(30~\text{V}\), and a resistance \(40.8~\Omega\)$$ all connected in series. If the ammeter has a coil of resistance \(480~\Omega\)$$ and a shunt of \(20~\Omega\)$$, then the reading in the ammeter will be:
1. \(0.5~\text{A}\)
2. \(0.02~\text{A}\)
3. \(2~\text{A}\)
4. \(1~\text{A}\)

A rectangular coil of length \(0.12~\text{m}\) and width \(0.1~\text{m}\) having \(50\) turns of wire is suspended vertically in a uniform magnetic field of strength \(0.2~\text{Wb/m}^2\). The coil carries a current of \(2~\text{A}\). If the plane of the coil is inclined at an angle of \(30^{\circ}\) with the direction of the field, the torque required to keep the coil in stable equilibrium will be:
1. \(0.15~\text{N-m}\)
2. \(0.20~\text{N-m}\)
3. \(0.24~\text{N-m}\)
4. \(0.12~\text{N-m}\)

A wire carrying current \(I\) has the shape as shown in the adjoining figure. Linear parts of the wire are very long and parallel to \(X\)-axis while the semicircular portion of radius \(R\) is lying in the \(Y\text-Z\) plane. The magnetic field at point \(O\) is:

An electron moving in a circular orbit of radius \(r\) makes \(n\) rotations per second. The magnetic field produced at the centre has a magnitude:
1. \(\frac{\mu_0ne}{2\pi r}\)
2. zero
3. \(\frac{n^2e}{r}\)
4. \(\frac{\mu_0ne}{2r}\)

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$\Omega$

If a charged particle (charge q) is moving in a circle of radius R at a uniform speed v, then the value of its associated magnetic moment μ will be:

1. $\frac{\mathrm{qvR}}{2}$

2. ${\mathrm{qvR}}^2$

3. $\frac{{\mathrm{qvR}}^2}{2}$

4. $\mathrm{qvR}$

In a mass spectrometer used for measuring the masses of ions, the ions are initially accelerated by an electric potential V and then made to describe semi-circular paths of radius R using a magnetic field B. If V and B are kept constant, the ratio of \(\big(\frac{\text{Charge on the ion}}{\text{Mass of the ion}} \big)\) will be proportional to:

1. $\frac{1}{R}$

2. $\frac{1}{R^2}$

3. $R^2$

4. R

A beam of electrons passes un-deflected through mutually perpendicular electric and magnetic fields. Where do the electrons move if the electric field is switched off and the same magnetic field is maintained?

When a charged particle with velocity $\overrightarrow{\mathrm{v}}$ is subjected to an induction magnetic field $\overrightarrow{\mathrm{B}}$, the force on it is non-zero. What does this imply?