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This mock test of WBJEE Physics Test - 12 for JEE helps you for every JEE entrance exam.
This contains 40 Multiple Choice Questions for JEE WBJEE Physics Test - 12 (mcq) to study with solutions a complete question bank.
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QUESTION: 1

A metallic wire of 40 Ω resistance is drawn to double its length. Its new resistance will be

Solution:
Resistance is a material property which is directly proportional to its length and inversely to its area. Here if the wire is drawn to double its length, then AREA WILL ALSO DECREASE TO ITS HALF. Therefore, the resistance is increased to 4 times the initial value. 4×40=160 Ω

QUESTION: 2

A wire of resistance 10 Ω is elongated by 10%, the resistance of the elongated wire is

Solution:

QUESTION: 3

If for material Young's modulus is 6.6 x 10^{10} N ∕ m^{2} and bulk modulus is 11 x 10^{10} N ∕ m^{2} then the Poisson's ratio is...

Solution:

QUESTION: 4

For high frequency, capacitor offers

Solution:

QUESTION: 5

A parallel plate capacitor is first charged and then a dielectric slab is introduced between the plates. The quantity that remains unchanged is

Solution:

QUESTION: 6

Suppose an electron is attracted towards the origin by a force k/r where 'k' is a constant and 'r' is the distance of the electron from the origin . By applying Bohr model to this system , the radius of the n^{th} orbital of the electron is found to be 'r'_{n} and the kinetic energy of the electron to be T_{n} . Then which of the following is true ?

Solution:

QUESTION: 7

A cylinder of radius r and length a is placed in a uniform in a uniform electric field E parallel to the axis of the cylinder. The total electric flux over the curved surface of cylinder is

Solution:

The electric flux entering and leaving the cylindrical surface is same

Φ = EπR^{2} - EπR^{2} = 0

where, E = electric field

R = radius of cylinder

Φ = outward flux

QUESTION: 8

If the radius of the earth were to shrink by 1% its mass remaining same, the acceleration due to gravity on the earth's surface would

Solution:

QUESTION: 9

A rocket with a lift-off mass 3.5 x 10^{4} kg is blasted upwards with an initial acceleration of 10m/s^{2}. Then the initial thrust of the blast is

Solution:

QUESTION: 10

Which of the following relations represent Biot-Savart's law?

Solution:

QUESTION: 11

A moving coil galvanometer of resistance 100 Ω shows full scale deflection when a current of 100 micro-amperes passes through it. If it is intended to show full scale deflection when a current of 1 milli-ampere passes through it, the value of shunt resistance in ohms to be connected to the galvanometer is

Solution:

QUESTION: 12

When 2 A current is passed through the coil of a tangent galvanometer, it gives a deflection of 45^{o}. For 60^{o }deflection, the current must be

Solution:

QUESTION: 13

A beaker containing a liquid of density (ρ) moves up with an acceleration (a). The pressure due to liquid at a depth (h) below the surface of the liquid is

Solution:

QUESTION: 14

A car travelling on a straight track moves with uniform velocity of ν₁ for some time and uniform velocity ν₂ for the next equal time. The average velocity of the car is

Solution:

QUESTION: 15

An object is projected with a velocity of 20 m/s making an angle of 45^{o} with horizontal. The equation for the trajectory is h = Ax - Bx^{2} where h is height, x is horizontal distance, A and B are constants. The ratio A : B is (g = 10 ms^{-2})

Solution:

QUESTION: 16

A 1 kg stone at the end of 1 m long string is whirled in a vertical circle at constant speed of 4 m/sec. The tension in the string is 6 N,when the stone is at (g = 10m/sec^{2})

Solution:

QUESTION: 17

Consider α -particles, β -particles and γ -rays, each having an energy of 0.5 MeV. In increasing order of penetrating powers, the radiations are

Solution:

QUESTION: 18

If the displacement of a particle executing S.H.M. is given by y= 0.30 sin (220t+0.64) in metre, then the frequency and maximum velocity of the particle is

Solution:

QUESTION: 19

Two springs of constants k₁ and k₂, have equal highest velocities, when executing SHM. Then, the ratio of their amplitudes (given their masses are eqaul) will be

Solution:

QUESTION: 20

'Mirage' is a phenomenon due to

Solution:

QUESTION: 21

The moment of inertia of a disc of mass M and radius R about an axis, which is tangential to circumference of disc and parallel to its diameter is

Solution:

QUESTION: 22

A disc is rotating with an angular velocity of ω. If a child sits on it, which of the following is conserved?

Solution:

QUESTION: 23

In p-n junction, avalanche current flows in circuit when biasing is

Solution:

QUESTION: 24

The state of the energy gained by valance electrons when the temperature is raised or when electric field is applied is called as

Solution:

QUESTION: 25

19*g* of water at 30 ^{o}*C* and 5*g* of ice at − 20 ^{o}C 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

Solution:

QUESTION: 26

A gas is being compressed adiabatically. The specific heat of the gas during compression is

Solution:

QUESTION: 27

Hertz is the unit of

Solution:

QUESTION: 28

If p=7i-2j+3k and q=3i+j+5k, then the modulus of p-2q is

Solution:

QUESTION: 29

A wavefront is an imaginary surface where

Solution:

QUESTION: 30

The work done in holding 15 Kg suitcase while waiting for a bus for 15 minutes is

Solution:

QUESTION: 31

Three block of masses m₁,m₂ and m₃ are connected by massless strings as shown on a frictionless table .They are pulled with a force T₃ = 40 N .If m₁ = 10 kg ,m₂ = 6 kg and m₃ = 4 kg, the tension T₂ will be

Solution:

QUESTION: 32

Which one of the following has not been expressed in proper units?

Solution:

QUESTION: 33

Two large metal sheets having surface charge densities σ and − σ are held parallel to each other at a small separation. The electric field at any point in the region between the sheets is

Solution:

QUESTION: 34

A standing wave on a string is given by y = (4 cm) cos [ π x] sin [50 π t], where x is in metre and t is in seconds. The velocity of the string section at x = 1/3 m at t = 1/5 s, is

Solution:

QUESTION: 35

A uniform smooth rod placed on a smooth horizontal floor is hit by a particle moving on the floor, at a distance l/4 from one end. Then, the distance travelled by the centre of the rod after the collision when it has completed three revolutions will be [ e ≠ 0, l is the length of the rod]

Solution:

QUESTION: 36

A coin is placed on a horizontal platform which undergoes horizontal S.H.M. about a mean position O. The coin does not slip on the platform. The force of friction acting on the coin is F.

Solution:

QUESTION: 37

H^{+}, He^{+} and O^{++} all having the same kinetic energy pass through a region in which there is a uniform magnetic field perpendicular to their velocities. The masses of H^{+}, He^{+} and O^{++} are 1 amu, 4 and 16 amu respectively. The

Solution:

QUESTION: 38

Hydrogen gas and oxygen gas have volume 1 cm^{3} each at N.T.P.

Solution:

QUESTION: 39

A ray incident on a droplet of water comes out of droplet after two refractions and one reflection. If the deviation suffered by the ray is to be minimum, the condition is

Solution:

QUESTION: 40

X-rays are produced in an X-ray tube operating at a given accelerating voltage. The wavelength of the continuous X-rays has values from

Solution:

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