Physics-
General
Easy
Question
A highly conducting ring of radius R is perpendicular to and concentric with the axis of a long solenoid as shown in fig. The ring has a narrow gap of width d in its circumference. The solenoid has cross sectional area A and a uniform internal field of magnitude B0. Now beginning at t = 0, the solenoid current is steadily increased to so that the field magnitude at any time t is given by B(t) = B0 + at where 
. Assuming that no charge can flow across the gap, the end of ring which has excess of positive charge and the magnitude of induced e.m.f. in the ring are respectively
- X, Aa
- X pR2a
- Y, pA2a
- Y, pR2a
The correct answer is: X, Aa
Since the current is increasing, so inward magnetic flux linked with the ring also increasing (as viewed from left side). Hence induced current in the ring is anticlockwise, so end x will be positive.
Induced emf 
Related Questions to study
physics-
The north and south poles of two identical magnets approach a coil, containing a condenser, with equal speeds from opposite sides. Then
The north and south poles of two identical magnets approach a coil, containing a condenser, with equal speeds from opposite sides. Then
physics-General
physics-
A conducting ring is placed around the core of an electromagnet as shown in fig. When key K is pressed, the ring
A conducting ring is placed around the core of an electromagnet as shown in fig. When key K is pressed, the ring
physics-General
physics-
Shown in the figure is a circular loop of radius r and resistance R. A variable magnetic field of induction 
is established inside the coil. If the key (K) is closed, the electrical power developed right after closing the switch is equal to
Shown in the figure is a circular loop of radius r and resistance R. A variable magnetic field of induction is established inside the coil. If the key (K) is closed, the electrical power developed right after closing the switch is equal to
physics-General
physics-
The resistance in the following circuit is increased at a particular instant. At this instant the value of resistance is 10W. The current in the circuit will be now
The resistance in the following circuit is increased at a particular instant. At this instant the value of resistance is 10W. The current in the circuit will be now
physics-General
physics-
A conducting rod PQ of length L = 1.0 m is moving with a uniform speed v = 2 m/s in a uniform magnetic field 
directed into the paper. A capacitor of capacity C = 10 mF is connected as shown in figure. Then
A conducting rod PQ of length L = 1.0 m is moving with a uniform speed v = 2 m/s in a uniform magnetic field directed into the paper. A capacitor of capacity C = 10 mF is connected as shown in figure. Then
physics-General
Maths-
Let f(x) = 
Assertion (A): Fundamental period of f(x) is 2
Reason (R) : period of sin x and cos x is 2
Let f(x) =
Assertion (A): Fundamental period of f(x) is 2
Reason (R) : period of sin x and cos x is 2
Maths-General
maths-
If (x1 ,y1) and (x2, y2) and ends of a focal chord of the parabola 
= 4ax, then square of G.M. of x1 and x2 is-
If (x1 ,y1) and (x2, y2) and ends of a focal chord of the parabola = 4ax, then square of G.M. of x1 and x2 is-
maths-General
physics-
A conductor ABOCD moves along its bisector with a velocity of 1 m/s through a perpendicular magnetic field of 1 wb/m2, as shown in fig. If all the four sides are of 1m length each, then the induced emf between points A and D is
A conductor ABOCD moves along its bisector with a velocity of 1 m/s through a perpendicular magnetic field of 1 wb/m2, as shown in fig. If all the four sides are of 1m length each, then the induced emf between points A and D is
physics-General
physics-
A square metallic wire loop of side 0.1 m and resistance of 1W is moved with a constant velocity in a magnetic field of 2 wb/m2 as shown in figure. The magnetic field is perpendicular to the plane of the loop, loop is connected to a network of resistances. What should be the velocity of loop so as to have a steady current of 1mA in loop
A square metallic wire loop of side 0.1 m and resistance of 1W is moved with a constant velocity in a magnetic field of 2 wb/m2 as shown in figure. The magnetic field is perpendicular to the plane of the loop, loop is connected to a network of resistances. What should be the velocity of loop so as to have a steady current of 1mA in loop
physics-General
physics-
A conducting wire frame is placed in a magnetic field which is directed into the paper. The magnetic field is increasing at a constant rate. The directions of induced current in wires AB and CD are
A conducting wire frame is placed in a magnetic field which is directed into the paper. The magnetic field is increasing at a constant rate. The directions of induced current in wires AB and CD are
physics-General
physics-
As shown in the figure a metal rod makes contact and complete the circuit. The circuit is perpendicular to the magnetic field with 
If the resistance is 
, force needed to move the rod as indicated with a constant speed of 
is
As shown in the figure a metal rod makes contact and complete the circuit. The circuit is perpendicular to the magnetic field with If the resistance is , force needed to move the rod as indicated with a constant speed of is
physics-General
physics-
As shown in the figure, P and Q are two coaxial conducting loops separated by some distance. When the switch S is closed, a clockwise current 
flows in P (as seen by E) and an induced current 
flows in Q. The switch remains closed for a long time. When S is opened, a current 
flows in Q. Then the directions of and (as seen by E) are
As shown in the figure, P and Q are two coaxial conducting loops separated by some distance. When the switch S is closed, a clockwise current flows in P (as seen by E) and an induced current flows in Q. The switch remains closed for a long time. When S is opened, a current flows in Q. Then the directions of and (as seen by E) are
physics-General
Maths-
A particle moves along a line by 
then S is decreasing when t 
A particle moves along a line by then S is decreasing when t
Maths-General
maths-
Assertion: f(x) = ln 
is an odd function.
Reason: Let f be a function with domain D such that
i) x D 
– x D
ii) f(–x) = – f(x) and
iii) f (0) = 0 or f (0) is not defined
Then the function f(x) is an odd function
Assertion: f(x) = ln is an odd function.
Reason: Let f be a function with domain D such that
i) x D – x D
ii) f(–x) = – f(x) and
iii) f (0) = 0 or f (0) is not defined
Then the function f(x) is an odd function
maths-General
physics-
A conducting rod of length 2l is rotating with constant angular speed w about its perpendicular bisector. A uniform magnetic field 
exists parallel to the axis of rotation. The e.m.f. induced between two ends of the rod is
A conducting rod of length 2l is rotating with constant angular speed w about its perpendicular bisector. A uniform magnetic field exists parallel to the axis of rotation. The e.m.f. induced between two ends of the rod is
physics-General
