Two circuits have coefficient of mutual induction of 0.09 henry. Average e.m.f. induced in the secondary by a change of current from 0 to 20 ampere in 0.006 second in the primary will be 

1. 120 V

2. 80 V

3. 200 V

4. 300 V

Two conducting circular loops of radii \(R_1\) and \(R_2\) are placed in the same plane with their centres coinciding. If \(R_1>>R_2\), the mutual inductance \(M\) between them will be directly proportional to:

A small square loop of wire of side l is placed inside a large square loop of wire of side L (L > l). The loop are coplanar and their centre coincide. The mutual inductance of the system is proportional to 

1. l / L

2. l² / L

3. L/l

4. L²/l

Two circular coils can be arranged in any of the three situations shown in the figure. Their mutual inductance will be 

1. Maximum in situation (A)

2. Maximum in situation (B)

3. Maximum in situation (C)

4. The same in all situations

The mutual inductance of a pair of coils is 2H. If the current  of the coil changes from 10A to zero in 0.1s, the emf induced in the other coil is – 

1.  2 V                     

2.  20 V 

3.  0.2 V                 

4.  200 V

Two coils of self-inductance \(2~\text{mH}\) and \(8~\text{mH}\) are placed so close together that the effective flux in one coil is completely linked with the other. The mutual inductance between these coils is:
1. \(10~\text{mH}\)
2. \(6~\text{mH}\)
3. \(4~\text{mH}\)
4. \(16~\text{mH}\)

Two coils of self-inductance L₁ and L₂ are placed so close together that they completely link the magnetic flux of each other. If M be their mutual inductance then, the correct relation is 

1. M = $\sqrt{\frac{L_1}{L_2}}$

2. M = L₁$\sqrt{L_2}$

3. M = L₁L₂

4. M = $\sqrt{L_1{L}_2}$

A circular ring of radius \(r\) is at the centre of a square having side  \(a\left ( a\gg r \right ).\) The mutual inductance of the system is:
1. \( \dfrac{\mu_0 r^2}{a}\)
2. \( \dfrac{\sqrt{2} \mu_0 r^2}{\pi} \)
3. \(\dfrac{2 \sqrt{2} \mu_0 r^2}{a}\)
4. \( \dfrac{2 \sqrt{2} \mu_0 r^2}{\pi a}\)

A small square-shaped loop of edge length l is placed at the centre of a circular loop A of radius r with its plane perpendicular to the plane of the circular loop. The coefficient of mutual induction of this combination is 

1. Zero

2. $\frac{{\mu }_0\sqrt{2}l{r}^2}{3\pi }$

3. $\frac{{\mu }_0\sqrt{2}{l}^{2}r}{3}$

4. $\frac{{\mu }_0\sqrt{3}{l}^2}{2r}$

Self inductances of two uncoupled coils are 40 mH and 90mH. Their mutual inductance is

1. 60 mH

2. 130 mH

3. 50 mH

4. Zero