WBJEE Physics Test - 7


40 Questions MCQ Test WBJEE Sample Papers, Section Wise & Full Mock Tests | WBJEE Physics Test - 7


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Attempt WBJEE Physics Test - 7 | 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

In an A.C. circuit, a resistance of R ohm is connected in series with an inductance L. If phase angle between voltage and current be 45º, the value of inductive reactance will be

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QUESTION: 2

An electron beam is subjected to perpendicular electric and magnetic fields of resectively. If there is no deflection, the velocity of electrons is

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QUESTION: 3

X - rays which can penetrate through longer distances in substances are called

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QUESTION: 4

A parallel plate condenser with oil between the plates (dielectric constant of oil K = 2) has a capacitance C. If the oil is removed, then capacitance of the capacitors becomes

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On removing the oil, the capacitance of the capacitor will become.

QUESTION: 5

The quantity of electricity needed to liberate one gram equivalent of an element is

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QUESTION: 6

Consider telecommunication through optical fibres. Which of the following statements is not correct

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QUESTION: 7

A microammeter has a resistance of 100 Ω and full scale range of 50 μA. It can be used as a voltmeter or as a higher range ammeter provided a resistance is added to it. Pick the correct range and resistance combination

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QUESTION: 8

The temperature coefficient of resistivity of material is 0.0004/K. When the temperature of the material is increased by 50ºC , its resistivity increases by 2 x 10-8   o h m -meter. The initial resistivity of the material in ohm-meter is

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QUESTION: 9

A wire of length L is drawn such that its diameter is reduced to half of its original diameter. If the initial resistance of the wire were 10 Ω, its new resistance would be

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QUESTION: 10

If the length of the wire is doubled and its area of cross section is decreased to half, then its resistance

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QUESTION: 11

The expected energy of the electrons at the absolute zero is called

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QUESTION: 12

A transformer is used to light a 100W and 110V lamp from a 220V mains. If the main current is 0.5A, the efficiency of the transformer is approximately

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QUESTION: 13

The effective value of a.c. in a circuit is 10 A. The peak value of current is

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QUESTION: 14

In a current carrying long solenoid, the field produced does not depend upon

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QUESTION: 15

Which of the following radiations have the least wavelength?

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QUESTION: 16

If the electric flux entering and leaving an enclosed surface respectively is φ 1 and φ 2 , the electric charge inside the surface will be

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QUESTION: 17

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

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QUESTION: 18

Two charges -10 C and + 10 C are placed 10cm apart. Potential at the centre of the line joining two charges is

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QUESTION: 19

Equal charges are given to two conducting spheres of different radii. The potential will

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QUESTION: 20

The capacitor of a parallel plate capacitor with no dielectric substance and a separation of 0.4 cm is 2 μF. The separation is reduced to half and it is filled with a substance of dielectric value 2.8. The new capacity of the capacitor is

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QUESTION: 21

A charged particle begins to move from the origin in a region which has a uniform magnetic field in the x-direction and a uniform electric field in the y-direction. Its speed is ν, when it reaches the point (x,y,z). The speed (ν) will depend upon

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QUESTION: 22

The path of particle moving under the influence of a force fixed in magnitude and direction is

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QUESTION: 23

In radioactive decay process, the negatively charged emitted β -particles are

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QUESTION: 24

What is the Q-value of the reaction

The atomic masses of 1H , 4H e and 7L i are 1.007825 u, 4.002603 u and 7.016004 u respectively

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QUESTION: 25

An alpha nucleus of energy bombards a heavy nuclear target of charge Ze. Then the distance of closest approach for the alpha nucleus will be proportional to

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QUESTION: 26

What is the stopping potential when the metal with work function 0.6 eV is illuminated with the light of 2 eV ?

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QUESTION: 27

The work function of a substance is 4.0 eV. The longest wavelength of light that can cause photoelectron emission from this substance is approximately

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QUESTION: 28

Time of exposure for a photographic print is 10 second, when a lamp of 50 Cd is placed at 1 m from it. Then another lamp of luminous intensity I is used, and is kept at 2 m from it. If the time of exposure now is 20 s, the value of I in (in Cd) is :

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QUESTION: 29

Two plane mirrors inclined to each other at an angle 72º , what is the number of images formed?

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QUESTION: 30

The minimum potential difference between the base and emitter required to switch a silicon transistor 'ON' is approximately

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QUESTION: 31

A p-n photodiode is made of a material with a band gap of 2.0 eV. The minimum frequency of the radiation that can be absorbed by the material is nearly

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QUESTION: 32

Energy gap in a metal is

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QUESTION: 33

In a P-type semiconductor the electrical conduction is due to

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QUESTION: 34

In intrinsic semiconductor at room temperature, number of electrons and holes are

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QUESTION: 35

The p-n junction diode is used as

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QUESTION: 36

When Ge crystal are doped with phosphorus atom then it becomes

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QUESTION: 37

Light was producing interference have their amplitudes in the ratio 3:2. The intensity ratio of maximum and minimum of interference fringes is

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QUESTION: 38

The ray of light

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QUESTION: 39

For which property are electrons used in an electron microscope?

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QUESTION: 40

According to wave theory, light is a form of energy which travels through a medium in the form of

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