Question # 1

A couple produces

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linear motion

rotational motion

both (A) and (B)

None

A listener observes the frequency “f” of stationary source. If it move toward with 3 times of velocity of sound. Then the apparent frequency of the sound will be

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f

3f

f/2

4f

A pulsating DC can be converted into constant voltage by using

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Filter

Full wave rectifier

Half wave rectifie

Bridge rectifier

A body of mass m having an initial velocity v, makes head on elastic collision with a stationary body of mass m. After the collision, the body of mass m comes to rest and only the body having mass M moves. This will happen only when:

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m>>M

m<<M

) m=M

m=1M

The distance covered by a body in time ‘t’ starting from rest is:

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1/2 𝑡²

vt

𝑎𝑡²

𝑎𝑡₂

When the length and area of cross-section both are doubled, then its resistance:

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Will become half

Will remain the same

Will be doubled

Will become four times

Choose incorrect about properties of photon

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Rest mass of photon is zero

A photon is never at rest

Photon is not deflected by electric field not by magnetic field

The velocity of photon is different in different media

A non-conducting semiconductor diode is:

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Forward biased

Poorly biased

Reverse biased

None of them

The coulomb’s law is valid for the charges which are:

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Moving and point charges

Stationary and point charges

Moving and non-point charges

Stationary and large size charges

The energy which an -e acquires when accelerated through a potential difference of 1 volt is called?

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1 Joule

1 Electron volt

1 Erg

1 Watt

The frequency and work function of an incident photon are n and𝝋𝟎. If f0 is the threshold frequency, then necessary condition for the emission of photo electron is:

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< 𝑓0

𝑓 ≥ 𝑓0

f = 𝑓0/2

None of these

de-Broglie wavelength associated with an electron moving at a speed of 1x106 ms-1 is

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4x10-10 ms-1

5x10-10 m

6x10-10 m

7x10-10 m

The ratio of the SI unit to the C)G.S unit of torque is.

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10⁷

10⁹

10⁰

10³

The fundamental frequency in a stretched string is 10 Hz. To double the frequency, the tension in it must be changed to:

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T₂ = 2T₁

T₂ = 4T₁

T₂ = T₁

none of these

A body of mass 3 Kg lies on the surface on the table 2m high. It is moved on the surface by 4m. The change of P.E will be:

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Zero

9.8 J

19.6 J

329 J

What happens to the centripetal acceleration of a particle, when its speed is doubled and angular velocity is halved?

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halved

doubled

remain unchanged

becomes four times

Temperature of black body radiating at 270c is increased to 327oc, then emittedenergywill increase by

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2 times

12 times

16 times

4 times

For atomic nucleus, the binding energy per nucleon with increase in mass number:

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Increases continuously

Remains same

Decrease continuously

First increases and then decreases with increase in mass number

Light of frequency 2 times the threshold frequency is incident on the metalsurface. Ifthe frequency is by quartered and intensity is doubled, the photoelectric becomes

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Quadrupled

Zero

Doubled

Halved

The efficiency of half wave rectifier is:

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25.6%

1.2%

40.6%

66.6%

A charge of 2C experiences a force 2000N in a uniform electric field. In this fieldthe potential difference between two points separated by a distance 1cm is

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2V

10V

5V

20V

The method by which only one half of A.C cycle is converted into direct current is called

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half wave amplification

half wave rectification

Full wave rectification

full wave amplification

Ultraviolet radiation of 6.2 eV falls on an aluminium surface having work function ∅ = 𝟒. 𝟐 𝒆𝑽.

The kinetic energy of the fastest electron emitted is:

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4 eV

2 eV

2.2 eV

1.2 eV

The angle of projection, at which the range of projectile would become half of its maximum value.

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45Degree

30Degree

15Degree

60 Degree

In Compton effect, it was considered that X-rays consist of:

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Electrons

Positrons

Photons

All of these

The power needed to lift amass of 5000g to height of 1min 2 second is

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2.45 watt

24.5 watt

245 watt

2.45 k watt

The work done to keep the satellite in the given orbit is.

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Zero

infinity

unit

can’t be decided

The minimum energy required by an electron to eject from metal surface is known as:

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Photo energy

Critical energy

Threshold energy

Work function

Avogadro number is known as number of molecules in:

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One kg of a substance

Unit volume of a substance

One mole of a substance

None of these

A ball is thrown vertically upwards. Neglecting air resistance, which statement is correct?

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The kinetic energy of the ball is greatest at the greatest height attained

The potential energy of the ball increase uniformly with time during the ascent

By the principle of conservation of momentum. The momentum of the ball is constant throughout its motion

By the principle of conservation of energy, the total energy of the ball is constant throughout its motion

A PN junction diode cannot be use:

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As rectifier

For converting light energy to electrical energy

For getting light radiation

For increasing the amplitude of an ac signal

In a full wave rectifier, the diode conducts during

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Both halves of the input cycle

A portion of the positive half cycle of the input

Positive half cycle of the input

Both halves of the input cycle

A steady current is flowing in a conductor of non-uniform cross-section. Thecharge passing through any cross-section per unit time is

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Directly proportional to the area of cross-section

Inversely proportional to the area of cross-section

Proportional to square of the area of cross-section

Independent of the area of cross-section

In full wave rectification, the output D.C. voltage across the load is obtainedfor

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The positive half cycle of input A.C. (C) The complete cycle of input A.C.

The negative half cycle of input A.C.

The complete cycle of

All of the above

electrons from the surface of a metal when:

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It is heated to a high temperature

Radiation of suitable wavelength falls on it

Electrons of suitable velocity strike it

It is placed in a strong electric field

De-Broglie received the Nobel prize in

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1929

1937

1928

1924

For a body moving with constant speed in a horizontal circle, which of the following remains constant?

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Velocity

Centripetal force

Acceleration

Kinetic energy

A tritium and alpha particle enter the magnetic field with same kinetic energy, what will be the ratio of their radii?

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3:4

√3: 1

√3: 4

√3:√2

A man has weight 980 N in a stationary lift. What will be his weight if the lift starts moving up with anacceleration of 4.9 ms^-2

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980 N

1470 N

1980 N

1460 N

Change in momentum per second is:

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Product force and time

Product of pressure and area

Ratio of pressure and area

None of these

An electron is moving towards high potential. Its electrical P.E:

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Increases

Remains constant

Decrease

May increase may decrease