WBJEE Physics Test - 3


40 Questions MCQ Test WBJEE Sample Papers, Section Wise & Full Mock Tests | WBJEE Physics Test - 3


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Attempt WBJEE Physics Test - 3 | 40 questions in 60 minutes | Mock test for JEE preparation | Free important questions MCQ to study WBJEE Sample Papers, Section Wise & Full Mock Tests for JEE Exam | Download free PDF with solutions
QUESTION: 1

The ratio of the energy of an X - ray photon of wavelength 1 Å to that of visible light of wave length 500 Å is

Solution:
QUESTION: 2

Two wires of the same metal have same length, but their cross-sectional areas are in the ratio 3 : 1. If resistance of the thicker wire is 10 Ω, then total resistance of the wires in series combination will be

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QUESTION: 3

The resistance of an incandescent lamp is

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QUESTION: 4

When a body is taken from the equator to the poles, its weight

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QUESTION: 5

In an ac circuit, with voltage V and current I the power dissipated is

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QUESTION: 6

According to Hooke's law force is proportional to

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QUESTION: 7

An infinite no. of capacitors with capacitances 1μF, 1/21μF, 1/41μF, 1/81μF, ...etc. are connected in parallel combination. Their equivalent capcitance will be

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QUESTION: 8

A capacitor of capacity 10 μ F is charged to 40V and a second capacitor of capacity 15 μ F is charged to 30V. If they are connected in parallel the amount of charge that flows from the smaller capacitor to higher capacitor in μ C is

Solution:


Amount of charge flowing = 10 x 40 − 10 x 34 = 60

QUESTION: 9

Rocket engines lift a rocket from earth surface, because hot gases with high velocity

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QUESTION: 10

The magnetic field at a point at a distance 'd' from the centre on axial line of a very short bar magnet of magnetic moment M is B. The magnetic field at a distance '2d' from centre on equitorial line of magnet of magnetic moment 8 M, will be

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QUESTION: 11

A long solenoid carrying a current produces a magnetic field B along its axis. If the current is doubled and the no. of turns per cm is halved, then new value of the magnetic field will be

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QUESTION: 12

An α-particle and a proton are accelerated at same potential difference from rest. Find the ratio of their final velocity?

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QUESTION: 13

When the free surface area of a liquid is increased, the surface tension of the liquid

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QUESTION: 14

The displacement is given by x=2t2+t+5, the acceleration at t=2s is

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QUESTION: 15

A body crosses the topmost point of a vertical circle with critical speed. Its acceleration, when the string is horizontal will be

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QUESTION: 16

A body is thrown horizontally from the top of a tower of height 5 m. It touches the ground at a distance of 10 m from the foot of the tower. The initial velocity of the body is (g = 10 ms⁻2)

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QUESTION: 17

Among electron, proton, neutron and α - particle the maximum penetration capacity is for

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QUESTION: 18

A body is executing S.H.M. when its displacement from the mean position is 4 cm and 5 cm, the corresponding velocity of the body is 10 cm/sec and 8 cm/sec. Then the time period of the body is

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QUESTION: 19

A body is executing simple harmonic motion with an angular frequency 2 rad/s. The velocity of the body at 20 mm displacement, when the amplitude of motion is 60 mm, is

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QUESTION: 20

The distance travelled by light in glass (refractive index =1.5) in a nanosecond will be

Solution:

Speed of light in glass
Distance travelled in one nanosecond
= 2 x 108 x 10-9 = 0.2 m = 20 cm

QUESTION: 21

Angular momentum is

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QUESTION: 22

The difference in the variation of resistance with temperature in a metal and a semiconductor arises essentially due to the difference in the

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QUESTION: 23

The moment of inertia of a thin uniform circular disc about one of the diameters is I. Its moment of inertia about an axis perpendicular to the circular surface and passing through the centre is

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QUESTION: 24

Two moles of monoatomic ideal gas at 60ºC are mixed adiabatically with one mole of another monoatomic ideal gas at 12ºC. The final temperature of the mixture is

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QUESTION: 25

P-type semiconductor is formed when
A. As impurity is mixed in Si
B. Al impurity is mixed in Si
C. B impurity is mixed in Ge
D. P impurity is mixed in Ge

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QUESTION: 26

A heat engine is a device

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QUESTION: 27

The dimensional formula for Planck's constant (h) is

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QUESTION: 28

When a star moves away from earth, the spectrum of the star shifts towards higher wavelength side. This is due to

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QUESTION: 29

If are a right handed triad of mutually perpendicular vectors of magnitude a, b, c, then the value of is

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QUESTION: 30

If the kinetic energy of a body changes by 20% then its momentum would change by

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QUESTION: 31

A block of ice at -10ºC is slowly heated and converted to steam at 100ºC .Which of the following curves represents the phenomenon qualitatively?

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QUESTION: 32

A student measures the focal length of a convex lens by putting an object pin at a distance u from the lens and measuring the distance v of the image pin. The graph between u and v plotted by the student should look like

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QUESTION: 33

A fish looking through the water sees the world contained in a circular horizon. If the refractive index of water is 4/3 and the fish is 12 cm below the surface, what is the radius of the circle?

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QUESTION: 34

Statement-1: Energy is released when heavy nuclei undergo fission or light nuclei undergo fusion .and
Statement-II: For heavy nuclei , binding energy per nucleon increases with increasing Z while for light nuclei it decrease with increasing Z .

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QUESTION: 35

A transparent solid cylindrical rod has a refractive index of It is surrounded by air. A light ray is incident at the midpoint of one end of the rod as shown in the figure.


The incident angle θ for which the light ray grazes along the wall of the rod is -

Solution:
*Multiple options can be correct
QUESTION: 36

A current is passing through a very thin loop of wire in the anticlockwise direction.

Solution:
*Multiple options can be correct
QUESTION: 37

The two ends of a spring are displaced along the length of the spring. All displacement have equal magnitudes. In which case or cases the tension or compression in the spring will have a maximum magnitude?

Solution:
*Multiple options can be correct
QUESTION: 38

M gm of a liquid of density ρ is filled in a light beaker and kept on a horizontal table as shown in the figure. The height of the liquid in the beaker is h. The beaker is wider on top than at its base and the cross-sectional area of the base is A. Neglect the effect of atmospheric pressure. Now, choose the correct statement(s) from the following.

Solution:
*Multiple options can be correct
QUESTION: 39

A parallel-plate capacitor fixed with a dielectric slab is connected to a battery. After the capacitor is fully charged, the dielectric is removed without disturbing the remaining circuit. Then

Solution:
*Multiple options can be correct
QUESTION: 40

The torque on a body about a given point is found to be equal to is a constant vector, and is the angular momentum of the body about that point. From this it follows that

Solution:
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