Mutual Induction

Q.

Two coils have a mutual inductance $5mH$. The current changes in the first coil according to equation $I=I_0\sin \omega t$, where, $I_0=10A$ and $\omega =100\pi rad/sec$. The maximum value of emf in the second coil is

1. $2\pi$

2. $5\pi$

3. $\pi$

4. $4\pi$

Q.

In inductance, there is opposition to the growth of current, it is due to

Q. In a step up transformer the turn ratio is 1:2, A lechlanche cell of e.m.f. 1.5V is connected across primary. The voltage across the secondary is

1. 3 V
2. 0.75V
3. 75 V
4. Zero

Q. An ideal inductor of inductance 100mh is connected to an ac source of220v 50Hz .find its inductive reactance

Q. 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. $l^2/L$
3. $L/l$
4. $L^2/l$

Q. Two coils have self-inductances $L_1=8mH$ and $L_2=4mH$. The current in one coil is increased at a constant rate. The current in the second coil is also increased at the same constant rate. At a certain instant of time, the current, the induced voltage and the energy stored in the first coil are $i_1,V_1$ and $W_1$. Corresponding values for the second coil are $i_2,V_2$ and $W_2$ respectively. Then:
(IIT-JEE 1994)

1. $\frac{i_1}{i_2}=4$
2. $\frac{V_1}{V_2}=\frac{1}{4}$
3. $\frac{W_1}{W_2}=\frac{1}{2}$
4. $\frac{i_1}{i_2}=\frac{1}{4}$

Q. The inner loop has an area of $5\times {10}^{-4}{\text{m}}^2$ and a resistance of $2\Omega$ (see figure). The larger circular loop is fixed and has a radius of $0.1m$. Both the loops are concentric and coplanar. The smaller loop is rotated with an angular velocity of $\omega rad{s}^{-1}$ about its diameter. The magnetic flux linked with the smaller loop is

1. $2\pi \times {10}^{-6}Wb$
2. $\pi \times {10}^{-9}Wb$
3. $\pi \times {10}^{-9}\cos \omega tWb$
4. Zero

Q. Two coils (1) & (2) are placed as shown in figure. Coefficient of mutual induction between (1) & (2) is M = 6 H. Find induced emf & induced current in coil (2). (R of coil (2) is $4\Omega )$

1. emf = 24 V, i = 0
2. emf = 0, i = 6A
3. emf = 24 V, i = 6A
4. emf = 0, i = 0

Q. Heater coil connected across a given potential difference has power P. Now the coil is cut into two equal halves and joined in parallel .Across the same potential difference this combination has power=?

Q. Two identical circular loops of metal wire are lying on a table without touching each other. Loop-A carries a current which increases with time. In response, the loop-B

1. Remains stationary
2. Is attracted by the loop-A
3. Is repelled by the loop-A​
4. Rotates about its CM, with CM fixed (CM is the centre of mass)
   

Q. In the circuit diagram shown, $X_C=100\Omega ,X_L=200\Omega$ & $R=100\Omega$. The effective current through the source is

Q. What will be the direction of current in the coil $A$ as the switch $S$ is closed?

1. Clockwise
2. Anticlockwise
3. Anticlockwise and then clockwise
4. Clockwise and then anticlockwise

Q. Current is a vector or scaler quantity