Physics Test 61...

In a transistor, the value of the base current depends on

A conducting square loop of side L and resistance R moves in its plane with a uniform velocity v perpendicular to one of its sides. A magnetic field B, constant in space and time, pointing perpendicular and into the plane of the loop, exists everywhere as shown in the figure given below. The current induced in the loop is

Two identical spheres A and B lie on a smooth horizontal circular groove at opposite ends of a diameter. A is projected along the groove and at the end of time t, it impinges on B. If e is the coefficient of restitution, the second impact will occur after a time

Two masses m and 2m are joined to each other by means of a frictionless pulley as shown in the figure below. When the mass 2m is released, the mass m will ascend with an acceleration of

Using mass (M), length (L), time (T) and current (A) as fundamental quantities, the dimensions of permeability are

A heavy nucleus at rest breaks into two fragments, which fly off with velocities in the ratio 8:1. The ratio of the radii of the fragments (assumed spherical) is

An escalator is moving downwards with a uniform speed u. A man of mass m is running upwards on it at a uniform speed v. If the height of the escalator is h, the work done by the man is going up the escalator is

How will the image formed by a convex lens be affected if the central portion of the lens is wrapped in black paper, as shown in the figure?

Two rods A and B of different materials are welded together as shown in the figure below. If their thermal conductivities are k₁ and k₂ respectively, the thermal conductivity of the composite rod will be

A potentiometer has a uniform potential gradient. The specific resistance of the material of the potentiometer wire is 10⁻⁷ ohm-meter and the current passing through it is 0.1 ampere, a cross-section of the wire is 10⁻⁶ m². The potential gradient along the potentiometer wire is: