WBJEE Physics Test - 1

Two similar wires under the same load yield elongation of 0.1 mm and 0.05 mm respectively. If the area of cross-section of the first wire is 4 mm², then the area of cross section of the second wire is

The mutual inductance of an induction coil is 5 H. In the primary coil, the current reduces from 5 A to zero in 10^-3s. What is the induced emf in the secondary coil ?

There is a uniform electric field of strength 10³ V m⁻¹ along Y-axis. A body of mass 1 gm and charge 10^{− 6}C is projected into the field from orgin along the positive X-axis with a velocity of 10 m s − 1 . Its speed in m s⁻¹ after 10s is (Neglect graviation )

Which of the following quantities does not depend upon the orbital radius of the satellite 

The centripetal acceleration of a body moving in a circle of radius 100 cm with a time period of 2s will be

A capacitor of capacity C₁ is charged upto V volt and then connected to an unchanged capacitor of capacity C₂. The potential difference across each capacitor will be

The coil of a moving coil galvanometer is wound over a metal frame in order to

If a bar magnet of moment μ is suspended in a uniform magnetic field B and it is given an angular deflection ' θ ' w.r.t its equilibrium position, the restoring torque on magnet is

The coil in the tangent galvanometer must be kept

Two mercury drops with radii in the ratio of 3 : 4 fall from a great height through the viscous liquid. The ratio of their terminal velocities is

The x and y coordinates of a particle at any time t are by x=7t+4t² and y=5t, where x and y are in metre and t in seconds. The acceleration of particle at t=5 s is

A bullet is fired from a gun with a velocity of 1000 m−s^-1 in order to hit a target 100 m away. At what height above the target should the gun be aimed? (Resistance of air is negligible and g = 10 m−s⁻2)

The centripetal acceleration is given by

Two radioactive substances A and B have decay constants 5 λ and λ respectively. At t = 0 they have the same number of nuclei. The ratio of number of nuclei of A to those of B will be after a time interval

The length of a simple pendulum is increased by 1%. Its time period will

One-fourth length of a spring of force constant K is cut away. The force constant of the remaining spring will be

A solid cylinder of mass M and radius R rolls on a flat surface. Its moment of inertia about the line of contact is

Which of the following spectrum has high to low frequency range?

A soild sphere, disc and solid cylinder all of the same mass and made of the same material are allowed to roll down (from rest) on an inclined plane, then

In forward biasing of junction diode, the width of depletion layer

In p-type semiconductor, majority current carriers are

Heat given to a body which rises its temperature by 1ºC is

The length and breadth of a metal sheet are 3.124 m and 3.002 m respectively. The area of this sheet up to four correct significant figures is

The vector     lies in the plane of vectors which of the following is correct ?

Doppler's effects in sound and light are

Two springs, having spring constants of 25 N-m⁻¹ and 16 N-m⁻¹are stretched by forces F₁ and F₂.If work done in stretching the springs is equal, then the ratio of the forces F₁ and F₂ is

An unknown resistance X is connected in the left gap and a known resistance R in the right gap of a meter bridge. The balance point is obtained at 55 cm from the left end of the wire. When R is increased by 5 Ω , the balance point shifts by 5 cm. The value of X is

The maximum range of a projectile fired with some initial velocity of found to be 1000 metre, in the absence of wind and air resistance. The maximum height h reached by this projectile is

The speed of a train increases at a constant rate α from zero to v and then remains constant for an interval and finally decreases to zero, at a constant rate β . The total time taken to cover a total distance l is given by

A bob of mass M is suspended by a massless string of length L. The horizontal velocity V at position A is just sufficient to make it reach the point B. The angle θ at which the speed of the bob is half of that at A, satisfies

Of two masses of 5 kg each falling from height of 10m, by which 2 kg water is stirred. The rise in temperature of water will be

Assuming the coefficient of friction between the road and tires of a car to be 0.5, the maximum speed with which the car can move around a curve of 40.0m radius without slipping if the road is unbanked, should be

A charged particle begins to move in a magnetic field, initially parallel to the field. The direction of the field now begins to change with its magnitude remaining constant. Choose incorrect statement(s) from the following.

A particle is moving in a circle of radius R in such a way that at any instant the radial acceleration and tangential acceleration are equal. Speed at t = 0 is v₀ and angular speed is ω₀ . Then

A small ball is connected to a block by a light string of length ℓ . Both are initially on the ground. There is sufficient friction on the ground to prevent the block from slipping. The ball is projected vertically up with a velocity u where 2gℓ < u² < 3gℓ . The centre of mass of the "block + ball" system is C. Then

A thin uniform rod of mass M and ℓ is suspended vertically from fixed end A. A small ball of mass m moving with a velocity v₀ collides normally at end B and gets stuck to it. Then

A point source of sound is emitting sound waves of frequency 1000 Hz. The source starts moving to the right with a speed of 32 m/s relative to ground while a reflecting surface which is on the righ side of source is approaching the source with a speed of 64 m/s relative to ground. The speed of sound in air is 332 m/s. For this situation, mark out the correct statement(s).