Lenz's Law

Q.

How can one increase the strength of induced current?

Q. An electron moves on a straight line path 'XY' as shown. The 'abcd' is a coil adjacent to the path of electron. What will be the direction of current, if any, induced in the coil?

1. No current induced
2. abcd
3. adcb
4. The current will reverse its direction as the electron goes past the coil

Q. For the given charge distribution on the ring, the net electric field at the centre of non-conducting ring is
(Assume the part of ring in first and third quadrant is neutral, second quadrant is positively charged, fourth quadrant is negatively charged)

Q. The current $‘i^{\prime }$ in an inductance coil varies with time $‘t^{\prime }$ according to the following graph


Which one of the following plots shows the variations of voltage in the coil magnitude wise? (all vertical lines are not part of graphs)

1. 
2. 
3. 
4. 

Q. Find the flux through the surface $\left(APB\right)$ of the given Gaussian surface containing a point charge $+9\text{nC}$ as shown in figure.
[$ABC$ is an equilateral triangle and take ${ϵ}_o=9\times {10}^{-12}{\text{C}}^2/{\text{N-m}}^2$]

1. $833{\text{N-m}}^2\text{/C}$
2. $933{\text{N-m}}^2\text{/C}$
3. $633{\text{N-m}}^2\text{/C}$
4. $733{\text{N-m}}^2\text{/C}$

Q. The direction of induced current or the polarity of induced emf can be found by

1. Kirchoff's law
2. Amber’s law
3. Lenz’s law
4. Lorentz’s law

Q. An electron moves on a straight line path 'XY' as shown. The 'abcd' is a coil adjacent to the path of electron. What will be the direction of current, if any, induced in the coil?

1. No current induced
2. abcd
3. adcb
4. The current will reverse its direction as the electron goes past the coil

Q.

Consider the situation given in the figure. The wire AB is slid on the fixed rails with a constant velocity. If the wire AB is replaced by a semicircular wire, the magnitude of the induced current will

1. decrease

2. increases

3. increase or decrease depending on whether the semicircle bulges towards the resistance or away from it

4. remain same

Q. A magnet NS is suspended from a spring and while it oscillates, the magnet moves in and out of the coil C. The coil is connected to a galvanometer G. Then as the magnet oscillates,

1. G shows deflection to the left and right with constant amplitude
2. G shows deflection on one side
3. G shows no deflection.
4. G shows deflection to the left and right but the amplitude steadily decreases.

Q. A small magnet $M$ is allowed to fall through a fixed horizontal conducting ring $R$. Let $g$ be the acceleration due to gravity. The acceleration of $M$ will be

1. $<g$ when it is above R and moving toward R.
2. $>g$ when it is above R and moving toward R.
3. $<g$ when it is below R and moving away from R.
4. $>g$ when it is below R and moving away from R.

Q. A short bar magnet is moved with constant velocity along the axis of a short coil. The magnet enters into the coil and then leaves it. The variation of induced emf $\left(\epsilon \right)$ with time $\left(t\right)$ is best represented as

1. 
2. 
3. 
4. 

Q. An electron moves along the line AB, which lies in the same plane as a circular loop of conducting wires as shown in the diagram. What will be the direction of current induced if any, in the loop

1. No current will be induced.
2. The current will be clockwise.
3. The current will be anticlockwise.
4. The current will change direction as the electron passes by.

Q. A short bar magnet is moved with constant velocity along the axis of a short coil. The magnet enters into the coil and then leaves it. The variation of induced emf $\left(\epsilon \right)$ with time $\left(t\right)$ is best represented as

1. 
2. 
3. 
4. 

Q. A magnet NS is suspended from a spring and while it oscillates, the magnet moves in and out of the coil C. The coil is connected to a galvanometer G. Then as the magnet oscillates,

1. G shows deflection to the left and right with constant amplitude
2. G shows deflection on one side
3. G shows no deflection.
4. G shows deflection to the left and right but the amplitude steadily decreases.

Q. The current $\left(I\right)$ in the inductance is varying with time ($t$) according to the plot shown in the figure.


Which one of the following is the correct variation of voltage with time in the coil?

Q. A bar magnet is thrown along the axis of a ring with speed $v_0$. After sometime, speed of magnet is $v$, then

1. $v>v_0$
2. $v<v_0$
3. $v=v_0$
4. Information is incomplete

Q. A conducting ring is placed around the core of an electromagnet as shown in fig. When key K is pressed, the ring: (Consider the ring is light weight)

1. Remains stationary.
2. Is attracted towards the electromagnet.
3. Jumps out of the core.
4. Revolves around the core.