Some magnetic flux is changed from a coil of resistance 10 ohm. As a result an induced current is developed in it, which varies with time as shown in figure. The magnitude of change in flux through the coil in webers is

(1) 2

(2) 4

(3) 6

(4) None of these

The graph gives the magnitude \(B(t)\) of a uniform magnetic field that exists throughout a conducting loop, perpendicular to the plane of the loop. Rank the five regions of the graph according to the magnitude of the emf induced in the loop, greatest first:

Figure (i) shows a conducting loop being pulled out of a magnetic field with a speed v. Which of the four plots shown in figure (ii) may represent the power delivered by the pulling agent as a function of the speed v

(1) a

(2) b

(3) c

(4) d

A flexible wire bent in the form of a circle is placed in a uniform magnetic field perpendicular to the plane of the coil. The radius of the coil changes as shown in the figure. The graph of induced emf in the coil is represented by

(1)

(2)

(3)

(4)

The current i in an induction coil varies with time t according to the graph shown in figure. Which of the following graphs shows the induced emf (e) in the coil with time

(1)

(2)

(3)

(4)

A square loop of side \(5\) cm enters a magnetic field with \(1\) cms^-1. If the front edge enters the magnetic field at \(t=0\), then which graph best depicts emf?

1.		2.
3.		4.

A long solenoid of diameter 0.1m has 2$\times {10}^4$ turns per meter. At the centre of the solenoid, a coil of 100 turns and radius 0.01m is placed with its axis coinciding with the solenoid's axis.  The current in the solenoid reduces at a constant rate to 0 A from 4A in 0.05s. If the resistance of the coil is $10{\pi }^2\Omega$, the total charge flowing through the coil during this time is 

1. 32$\mathrm{\pi \mu C}$

2. 16$\mu C$

3. 32$\mu C$

4. 16$\mathrm{\pi \mu C}$

A uniform magnetic field is restricted within a region of radius r. The magnetic field changes with time at a rate $\frac{dB}{dt}$, Loop 1 of radius R is outside the region of magnetic field as shown in the figure. Then, the emf generated is

(1) zero in loop1 and zero in loop 2

(2) $-\frac{dB}{dt}{\mathrm{\pi r}}^2 \mathrm{in} \mathrm{loop} 1 \mathrm{and}-\frac{\mathrm{dB}}{\mathrm{dt}}{\mathrm{\pi r}}^2 \mathrm{in} \mathrm{loop} 2$

(3) $-\frac{dB}{dt}{\mathrm{\pi r}}^2 \mathrm{in} loop 1 and zero \mathrm{in} \mathrm{loop} 2$

(4) $\frac{dB}{dt}{\mathrm{\pi r}}^2 \mathrm{in} loop 1 and zero \mathrm{in} \mathrm{loop} 2$

A wire loop is rotated in a magnetic field. The frequency of change of direction of the induced emf is

(1) once per revolution

(2) twice per revolution

(3) four times per revolution

(4) six times per revolution

A coil of resistance 400$\Omega$ is placed in a magnetic field. If the magnetic flux $\varphi \left(Wb\right)$ linked with the coil varies with time t (sec) as $\varphi =50t^2+4.$

The current in the coil at t=2s is 

(1) 0.5A                                           

(2) 0.1A

(3) 2A                                               

(4) 1A