List of practice Questions

A heat engine operates between a cold reservoir and a hot reservoir. The engine takes 200 J of heat from the hot reservoir and has the efficiency of 0.4. The amount of heat delivered to the cold reservoir in a cycle is:
Two metallic solid spheres A and B,have radius R and 3R,respectively. The solid spheres are charged and kept isolated. Then,the two spheres are connected to each other through a thin conducting wire. The ratio of the final charge on the spheres A to B is:
The work done W is required by an agent to form a bubble of radius R. An extra amount of work △W is required to increase the radius by △R. If \(\frac{△R}{R}\)=1%,\(\frac{△W}{W}\) is:
A hollow sphere of radius 'r' encloses an electric dipole composed of two charges +q and -q. The net flux of electric field through the surface of the sphere due to the enclosed dipole is:
A Spherical ball is subjected to a pressure of 100 atmosphere. If the bulk modulus of the ball is 1011 N/m2,then change in the volume is:
A string clamped at both the ends has a mass 10gm. length 1m and it is kept under tension of 1N. It is vibrating in the fundamental mode with an amplitude of 1cm .Assuming the standing wave pattern, the maximum acceleration seen in the string is
Line-of-sight communication happens by means of :

A NOR gate has two input I1 and l2,and one output terminal Y. Which of the following configuration (truth table) is INCORRECT for the NOR gate?

Two identical solid spheres,each of radius 10cm,are kept in contact. If the mass of inertia of this system about the tangent passing through the point of contact is 0.14 kg.\(m^2\) Then mass of each sphere is:

Two satellites A and B are moving around the earth in a circular orbit of radius 2R,respectively. If the kinetic energy of the satellite A is two-times the kinetic energy of the satellite B,the ratio of their masses (mA:mB) is:
An object at rest suddenly explodes into three parts of equal masses. Two of the away at right angles to each other with equal speed of 10 m/s. The speed of the just after the explosion will be: 
A billiard ball of mass ‘M’ moving with velocity ‘v1’ collides with another ball of the same mass but at rest. If the collision is elastic the angle of divergence after the collision is
A projectile is thrown at an angle 60° above the horizontal and with kinetic energy. The kinetic energy of the projectile at the highest point of its trajectory will be:

A radioactive nuclei has a half life of 693s. The activity of one mole of that nuclei sample is:(Avogadro's number=6.023 x1023 and In(2)=0.693) 

A gun fires N bullets per minute. The mass of each bullet is 10g and every bullet travels With a speed of 600m/s. If the power delivered by the gun is 9000W,the value of N is:

A glass capillary of radius 0.15 mm is dipped into a liquid of density and surface tension 1600 kg/m3 and 0.12 Nm-1,respectively. The liquid in the capillary rises by a height of 5.0 cm. The contact angle between liquid and glass will be:(Take g=10 ms-2)

A body undergoing a straight line motion is under the influence of source of constant power. How does its displacement very with time?

The angle of minimum deviation for a prism of apex angle 60° and refractive index of \(\sqrt{2}\) is:

Select the incorrect statement about friction:
A metal wire of natural length 50cm and cross-sectional area 4.0 mm2 is fixed at end. A mass of 2.4kg is hung from the other end of the wire. If the elastic pot energy of the wire is 1.8x10-4J,then its Young's modulus is:(Take g=10 ms-2)
An average frictional force of 80N is required to stop an object at a distance of 25m. If the initial speed of the object is 20m/s,the mass of the object is:
In a Zener regulated power supply circuit as shown in figure below,a Zener diode with Vz=1OV is used for regulation. The load current,Zener current and unregulated input Vin are 5mA,35mA and 20V,respectively. The value of R is:
A wheel is rolling on a plane surface. A point on the rim of the wheel at the same level as the Centre has a speed of 4m/s. The speed of the Centre of the wheel is:
A uniform thin rod of mass 3kg has a length of 1m. If a point mass of 1kg is attached to it at a distance of 40cm from its center,the center of mass shifts by a distance of: 

A train consists of an engine and 3 coaches, first coach is closest to the engine, third coach is farthest from engine. The train is moving with a constant acceleration a. The mass of each coach is M. The force exerted by the first coach on the second coach will be: