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The RMS voltage shown in the waveform is

Solution:... View Article

A short bar magnet passes at a steady speed right through a long solenoid. A galvanometer is connected across the solenoid which graph best represents the variation of the galvanometer deflection 0 with time.

a) b) c) d) Solution: Option a). Explanation: Here, the presence of a non uniform field is seen due to the presence of the bar magnet. The... View Article

A parallel beam of light ray parallel to the X-axis is incident on a parabolic reflecting surface x=2by^2 as shown in the figure. After reflecting it passes through focal point F. What is the focal length of the reflecting surface?

Solution: for a parabolic curve Where, a=focal length... View Article

A particle executing SHM has a maximum speed of 30cms−1 and a maximum acceleration of 60cms−2 . What is the period of oscillation?

Solution: Maximum velocity Maximum acceleration A=2 cms w=30/2 = 15sec−1 T=2\pi/w... View Article

A thin rod of mass m and length 2l is made to rotate about an axis passing through its centre and perpendicular to it. Its angular velocity changes from 0 to ω in time t. What is the torque acting on the rod?

Solution: Since l=2l Inertia of the rod is given by,... View Article

If all linear dimensions of an inductor are tripled, then self inductance will become (keeping total number of turns per unit length constant).

a) 2 times b) 3 times c) 9 times d) 27 times Solution: d) 27 times Explanation: when l is tripled, L\propto (3l)^{3} L\propto 27l^{3}... View Article

When slightly different weights are placed on the two pans of a beam balance, the beam balance comes to rest at an angle with the horizontal. The beam is supported at a single point P by a pivot. Then which of the following statement (s) is (or are) true?

a) The net torque about P due to the two weights is non-zero at the equilibrium position. b) The whole system does not continue to rotate about P... View Article

A magnetic wire of dipole moment 4π Am^{2} is bent in the form of a semi-circle. The new magnetic moment is?

a) 1\pi Am^{2} b) 2\pi Am^{2} c) 8i Am^{2} d) 4\pi Am^{2} Solution: c) 8i Am^{2}... View Article

Why is electrostatic potential constant throughout the volume of the conductor and has the same value (as inside) on its surface?

Solution:The electric field inside the conductor is zero. Or V_{1}=V_{2} means that the potential at every point is the same inside the... View Article

A proton, a deuteron and an α-particle accelerated through the same potential difference enter a region of uniform magnetic field, moving at right angles to B. What is the ratio of their kinetic energies?

Solutions: Kinetic energy gained by a charged particle of charge q when accelerated under a potential difference V will be KE=qV For a given V:... View Article

A man is swinging on a swing made of 2 ropes of equal length L and in direction perpendicular to the plane of paper. The time period of the small oscillations about the mean position is

a) b) c) d) The correct answer is a) The motion of the swing is the same as the motion of a simple pendulum, in which there is a... View Article

A soldier walks forwards a high wall taking 120steps per minute. When he is at a distance of 90m from the wall he observes that echo of step coincides with the next step. The speed of sound must be?

Solution: In a second, two steps are heard, hence 1 step is heard in 0.5 seconds. Speed= Distance/time Speed = 180/0.5 = 360m/s... View Article

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