A laser beam is coherent because it contains

 According to Huygens’ principle, light is a form of

The displacement in metres of a body varies with time t in second as y = t2 – t – 2. The displacement is zero for a positive of t equal to

The force required to produce an acceleration of 2 m/s² on a mass of 2 kg is

A machine gun fires a bullet of mass 40 g with a velocity of 1200 ms-1. The man holding it can exert a maximum force of 144 N on the gum. How many bullets can he fire per second at the most?

A passenger in a moving bus is thrown forward when the bus is suddenly stopped. This is explained

A body of mass 1 kg is attached to one end of a wire and rotated in a horizontal circle of diameter 40 cm with a constant speed of 2 m/s. What is the area of cross-section of the wire if the stress developed in the wire is 5 × 106 N/m²?

In a wire, when elongation is 2 cm energy stored is E. if it is stretched by 10 cm, then the energy stored will be

Spring is pulled down by 2 cm. What is amplitude of motion?

 A thin uniform, circular ring is rolling down an inclined plane of inclination 300 without slipping. Its linear acceleration along the inclined plane will be

Moment of inertia depends on

 If a body is rotating about an axis, passing through its centre of mass then its angular momentum is directed along its

Which of the following pairs has the same dimensions?

Loudness of a note of sound is

The frequency of the note produced by plucking a given string increases as

A ball is dropped from a height of 1 m. If the coefficient of restitution between the surface and ball is 0.6, the ball rebounds to a height of

A quantity of work of 1000 J is done in 2 seconds. The power utilised is

A room temperature the r.m.s. The velocity of the molecules of a certain diatomic gas is found to be 1930 m/sec. the gas is

Hook’s law is used for defining which of the following?

For which of the following processes, the thermal conduction is maximum?

A well stoppered thermos flask contains some ice cubes. This is an example of

The least random state of the water system is

Considering entropy(S) thermodynamic parameters the criteria for the spontaneity of any process is

The sensitivity of a tangent galvanometer can be increased by increasing

The permeability of a paramagnetic substance is

Which of the following shows that the earth behaves as a magnet?

If an electric dipole is kept in a uniform electric field then resultant electric force on it is

Two copper spheres of the same radius, one solid and the other hollow, are charged to the same potential. Which will have more charge?

The capacitance of a capacitor will decrease if we introduce a slab of

Energy dissipated in LCR circuit in

Given three equal resistors, how many different combinations (taken all of them together) can be made?

Specific resistance of ali metals is mostly affected by

The example of a non-ohmic resistance is

The coupling coefficient of the perfectly coupled coils is

With fall of temperature, the forbidden energy gap of a semiconductor

In a p-type semiconductor, current conduction is by

The relation between number of free electrons (n) in a semiconductor and temperature (T) is given by

A radioactive nucleus emits a beta particle. The parent and daughter nuclei are

The number of beta particles emitted by a radioactive substance is twice the number of alpha particles emitted by it. The resulting daughter is an

The strength of photoelectric current depends upon

In photoelectric emission, for alkali metals the threshold frequency lies in the

Which of the following cannot be polarised?

Light year is the unit of

A single slit diffraction pattern is obtained using a beam of red light. What happens when the red light is replaced by the blue light?

When a polaroid is rotated, the intensity of light varies but never reduces to zero. It shows that the incident light is