A rectangular loop carrying a current \(I_1,\) is situated near a long straight wire carrying a steady current \(I_2.\) If the wire is parallel to one of the sides of the loop and is in the plane of the loop as shown in the figure, then the current loop will:
          
1. move away from the wire.
2. move towards the wire.
3. remain stationary.
4. rotate about an axis parallel to the wire.

A milliammeter of \(10\) mA has a coil resistance of \(1~\Omega\). To use it as an ammeter of range \(1\) A, the required shunt must have a resistance of:

1. \(\frac{1}{101}~\Omega \)

2. \(\frac{1}{100}~\Omega \)

3. \(\frac{1}{99}~\Omega \)

4. \(\frac{1}{9}~\Omega \)

Two toroids \(1\) and \(2\) have total no. of turns \(200\) and \(100\) respectively with average radii \(40~\text{cm}\) and \(20~\text{cm}\) respectively. If they carry the same current \(i,\) what will be the ratio of the magnetic fields along the two loops?
1. \(1:1\)
2. \(4:1\)
3. \(2:1\)
4. \(1:2\)

A ring of radius \(R\) carries a linear charge density \(\lambda\). It is rotating with angular speed \(\omega\) about an axis passing through the centre and perpendicular to the plane. What is the magnetic field at its centre?

Two circular coils \(1\) and \(2\) are made from the same wire but the radius of the \(1\)^st coil is twice that of the \(2\)^nd coil. What is the ratio of the potential difference applied across them so that the magnetic field at their centres is the same?
1. \(3\)
2. \(4\)
3. \(6\)
4. \(2\)