Physics Test - ...

Half-life of a radioactive substance A is 4 days. The probability of a nucleus that,  from the given sample that it will decay in two half-lives is

A block of mass m is connected rigidly with a smooth wedge (plank) by a light spring of stiffness k. If the wedge is moved with constant velocity v0, find the work done by the external agent till the maximum compression of the spring.

Three capacitors each of capacity 4 μF are to be connected in such a way that the effective capacitance is 6 μF. This can be done by

An elevator is going upward with an acceleration a = g/4 and a ball is released from rest relative to the elevator at a distance h₁ above the floor. The speed of the elevator at the time of ball release is v₀. Then the bounce height h₂ of the ball with respect to the elevator is (the coefficient of restitution for the impact is e)

Three point charges Q, +q and +q are placed at the vertices of a right angled isosceles triangle as shown. The net electrostatic energy of the configuration is zero, if Q is equal to

A particle is projected vertically upwards with a velocity u, from a point O. When it returns to the point of projection, which of the following is incorrect ?

An inverted bell, lying at the bottom of lake 47.6 m deep, has 50 cm³ of air trapped in it. The bell is brought to the surface of lake. The volume of the trapped air will become (atmospheric pressure = 70 cm of Hg and density of Hg = 13.6 g/cm³)

An electron is in an excited state in a hydrogen like atom. It has a total energy of -3.4 eV. The kinetic energy is E and its de Broglie wavelength is λλ. Then

A clock, which keeps correct time at 25^oC, has a pendulum made of brass. The coefficient of linear expansion for brass is 0.000019 ^oC-1. How many seconds a day will it gain if the ambient temperature falls to 0^oC ?

Two blocks each of mass m,  lie on a smooth table. They are attached to two other masses as shown in figure. The pulleys and strings are light. An object O is kept at rest on the table. The sides AB and CD of the two blocks are made reflecting. The acceleration of two images formed in those two reflecting surfaces with respect to each other is