WBJEE Physics Test - 14 - JEE MCQ

The work done in stretching a wire by 1mm is 2J. The work necessary for stretching another wire of same material but with double the radius of cross-section and half the length by 1mm is in Joules

An electric dipole of dipole moment p is placed in uniform electric field of strength E. If θ is the angle between p and E, then potential energy of the dipole becomes maximum, when θ is

Eddy currents are produced when

There are two bodies of masses 100 kg and 10,000 kg separated by a distance 1 cm. At what distance from the smaller body, the intensity of gravitational field will be zero

An electric dipole consists of two opposite charges of magnitude  q seperated by 2a. When the dipole is placed in uniform electric field E, to have minimum potential energy, then dipole moment p makes which the following angle with E

If the force on a rocket moving with a velocity of 300 m−s^-1 is 210 N, then the rate of fuel combustion is

A cell is connected between two points of a uniformly thick circular conductor. i₁ and i₂ are the currents flowing in two parts of the circular conductor of radius a. The magnetic field at the centre of the loop will be

If an ammeter is to be used in place of voltmeter, then we must connect with the ammeter a

Force between two identical bar magnets whose centres are r metre apart is 4.8 N when their axes are in the same line. If the separation is increased to 2 r meters, the force between them is reduced to

The shape of a liquid drop becomes spherical due to its

A body projected vertically upwards with a velocity u returns to the starting point in 4 s. If g=10 m−s^-2, the value of u is

A boat is sent across a river with a velocity of 8 km h^-1. If the resultant velocity of boat is 10 km h^-1, then the velocity of river is

An aeroplane moving horizontally with a speed of 720 km-h^-1 drops a food packet, while flying at a height of 405 m. The time taken by the food packet to reach the ground and its horizontal range is (Take g = 10 m−s^-1)

The first atomic reactor was constructed by

An instantaneous displacement of a simple harmonic oscillator is x = A cos (ωt + π/4 ). Its speed will be maximum at time

A prism is made up of material of refractive index 3 . The angle of the prism is A. If the angle of minimum deviation is equal to the angle of the prism, then the value of A is

The moment of inertia of a straight thin rod of mass M and length l about an axis perpendicular to its length and passing through its one end, is

A particle has simple harmonic motion. The equation of its motion is x =5 sin (4t-π/6), where x is its displacement. If the displacement of the particle is 3 units, then its velocity is

A solid cylinder of mass M and radius R rolls down an inclined plane without slipping. The speed of its centre of mass when it reaches the bottom is

In case of a semiconductor which of the following statement is wrong

Wires P and Q have the same resistance at ordinary(room) temperature. When heated resistance of P increases and that of Q decreases. We conclude that

19g of water at 30 ^oC and 5g of ice at − 20 ^oC are mixed together in a calorimeter. What is the final temperature of the mixture ? Given specific heat of ice = 0.5 cal g^{-1  o}C^-1 and latent heat of fusion of ice = 0.8 cal g^-1

A mass of liquid with volume V₁ is completely changed into a gas of volume V₂ at a constant external pressure P and temprature T. If the latent heat of evaporation for the given mass is L, then the increase in the internal energy of the system is

Measurement of current will be more accurate, when it is measured by

If are vectors forming a reciprocal system to the vectors  then is equal to

In Young's double slit interference experiment the wavelength of light used is 6000 Å . If the path difference between waves reaching a point P on the screen is 1.5 microns, then at that point P

Two equal masses m₁ and m₂ moving along the same straight line with velocities + 3m/s and -5 m/s respectively collide elastically. Their velocities after the collision will be respectively