A straight wire of length ${\left(\mathrm{\pi }\right)}^2$ metre is carrying a current of 2 A and the magnetic field due to it is measured at a point distance 1 cm from it. If the wire is to be bent into a circle and is to carry the same current as before, the ratio of the magnetic field at its center to that obtained in the first case would be

1. 1:100

2. 100:1

3. 1:50

4. 50:1

A current-carrying wire is placed in non-conducting liquid medium of refractive index n and relative electrical permittivity ${\epsilon }_r$. Then magnetic field at a point r distance of the point from the element is given by

1. $\frac{{\mu }_0}{4\mathrm{\pi }}\frac{l\overrightarrow{dl}\times \hat{r}}{r^2}$

2. $\frac{{\mu }_0{\mu }_r}{4\mathrm{\pi }}\frac{l\overrightarrow{dl}\times \hat{r}}{r^2}$

3. $\frac{{\mu }_0}{4\mathrm{\pi }}\frac{I\overrightarrow{dl}\times \hat{r}}{r^2}\left(\begin{array}{c}\frac{n^2}{{\epsilon }_r}\end{array}\right)$

4. Both (2) & (3)

Magnetic field due to straight current-carrying conductor is 

1. Radially inward 

2. Radially outward 

3. Square shaped

4. Concentric and circular

The Ampere law is based on which theorem?
1. Green’s theorem
2. Gauss divergence theorem
3. Stoke’s theorem
4. Maxwell theorem

To which law of electricity is Biot Savart law of magnetism analogous to

1. Coulomb's law

2. Ohm's law

3. Kirchoff's law

4. Faraday's law

Given below are two statements: 
 

In which of the following situations will there be no force?

1. A positive charge projected past a bar magnet

2. A positive charge sent along the axis of a solenoid 

3. Two parallel wires carrying current in the same direction

4. A positive charge projected between the poles of a magnet 

Torque on a current-carrying coil is maximum in a uniform magnetic field, when

1. Plane of the coil makes an angle ${45}^{\circ }$ with the field

2. Plane of the coil is perpendicular to the field

3. Plane of the coil is parallel to the field

4. Plane of the coil makes an angle ${60}^{\circ }$ with the field

The current sensitivity of a moving coil galvanometer is \(1~\text{rad /A}\) and its resistance is $\mathrm{}$\(5~\Omega\). Its voltage sensitivity is:
1. \(0.2~\text{rad/V}\)
2. \(0.1~\text{rad/V}\)
3. \(1~\text{rad/V}\)
4. \(2~\text{rad/V}\)

A wire abcdef with each side of length L bent as shown and carrying a current I is placed in a uniform magnetic field B parallel to the positive y-direction. What is the magnitude and direction of the force experienced by the wire?

1. BIL along +z-direction

2. BIL along +y-direction

3. BIL along -z-direction

4. BIL along -y-direction