Question # 1

According to Bohr’s theory, a line in the Ballmer series arises when the electron jumps from any of the higher orbits to the orbit with quantum number:

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1

2

3

4

According to boyle's law, volume of a given mass of a gas is

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Inversely proportional mass at constant pressure

Directly proportional to pressure at constant temprerature

Inversely proportional pressure at constant temprature

None of these

Angular displacement in rotational motion is expressed in

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m

m²

Nms-1

Nm s

For a particle in circular motion the centripetal acceleration

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may be more or less than its tangential acceleration

equal to its tangential acceleration a

more than its tangential acceleration

less than its tangential acceleration

The stopping potential for a certain metal is 10 volt, the max. Energy of emitted electron is:

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10 J

100 J

1.6 × 10-18 J

1.6 × 10-19 J

In thermodynamics, the change in internal energy depends upon:

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The path taken between initial and final states

The initial state only

The final state only

Initial and final states

A body is moving in a circle with a constant speed. it has

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a constant velocity

a constant acceleration

a velocity of constant magnitude

an acceleration of constant magnitude

A force 𝑭 = (𝟓𝒊̂+ 𝟑𝖩̂) newton is applied over a particle which displaces it from its origin to the point 𝒓 = (𝟐𝒊̂− 𝟏𝖩̂) meters. The work done on the particle is:

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– 7 joules

+13 joules

+ 7 joules

+11 joules

Petrol engine coverts ____________ of available heat energy into work.

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20% to 25%

25% to 30%

30% to 35%

35% to 40%

The angular momentum of a body changes from 30 J-S to 50 J-S in 0.5 sec. The torque acting on it is

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40 N-m

100 N-m

50 N-m

150 N-m

In which process, the change in internal energy of the system of zero:

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Isochoric process

isobaric process

Adiabatic process

Isothermal process

The direction of force experienced by a moving in a magnetic field will be:

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Parallel to the field

Opposite to the field

Parallel to its direction of motion

Perpendicular to both the field and the velocity vector

The power output of a full wave rectifier is:

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Equal to H.W.R

Twice of H.W.R

Half of H.W.R

Four times of H.W.R

When a dielectric is inserted between the plates of a capacitor, Which one is true

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Energy stored increase

Energy stored decrease

Capacitance decrease

All

Swimming is possible on account of

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1^st law of motion

2^nd law of motion

3^rd law of motion

Newton’s law of Gravitation

The magnetic field of a solenoid is quite similar to that of a:

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Straight conductor

A horse shoe magne

Any magnet

A bar magnet

A long solenoid has 20 turns/ cm. The current necessary to produce a magnetic field of 20 mellites inside the solenoid is approximately:

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1A

2A

4A

8A

The direction of angular velocity is along

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Tangent to the circle

Axis of rotation

Inward the radius

Out ward of the radius

In an 𝑎 −decay:

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The parent and daughter nuclei have same number of protons

The daughter nucleus has one proton more than parent nucleus

The daughter nucleus has two protons less than parent nucleus

The daughter nucleus has two neutrons more than parent nucleus

Which of the following does not have the same units:

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Work

Heat

Kinetic energy

Power

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 radioactive substance has a half-life of 4 months. Three-fourths of the substance will decay in:

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5months

6months

8months

7months

Initially, four identical uniform blocks, each of mass m and thickness h, are spread on a table How much work is done on the blocks in stacking them on top of one another?

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2 mgh

3 mgh

4mgh

6mgh

The photoelectric effect was explained by:

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Einstein

Davison

Hertz

Planck

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

Light of frequency 1.5 times the threshold frequency is incident on a photo sensitive material. If the frequency is halved and intensity is doubled the photo electric current becomes

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Four times

Half

Double

Zero

An electric room radiator, which operates at 50V has resistance of 50 Ω. Power of the radiator is approximately:

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100W

50W

450W

1000W

The rate of decay radioactive substance:

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Is constant

Decrease exponentially with time

Varies inversely with time

Decrease linearly with time

The momentum of a particle is numerically equal to its K.E. What is the velocity of a particle?

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9 ms^-1

3 ms^-1

2 ms-1

1 ms^-1

A whistle is revolved with high speed in a horizontal circle of radius R. to an observer at the centre of the circle the frequency of the whistle will appear to be:

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Decreasing

Increasing

Both

Constant

If C_vdonotes molar specific heat at constant volume and𝜟 T is the change in temperature, then C_v𝜟T gives:

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Volume

Pressure

Energy

Entropy

. Time rate of change of momentum is equal to

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Force

Impulse

Velocity

Both A and C

An electric motor exerts a force of 40 N on a cable and pulls it by a distance of 30 m in one minute. The power supplied by the motor in watts is

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20

200

2

10

Between the plates of a parallel plate condenser there is 1mm thick paper of dielectric constant 4. Itis charged at 100 volt. The electric field in volt/meter between the plates of the capacitor is:

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100

25000

100000

400000

A stone is thrown upwards it returns to ground describing a parabolic path which of the following remains constant:

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Speed of the ball

Kinetic energy of the ball

Vertical component of velocity

) Horizontal component of velocity

Kinetic energy of a body moving with speed of 10 ms-1 is 30 J. If its speed becomes30 ms-1 then its K.E becomes

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10J

270 J

90J

180 J

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

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Increases

Remains constant

Decrease

May increase may decrease

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

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Zero

infinity

unit

can’t be decided

The number of electrons in a nucleus X of atomic number Z and mass number A is:

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A

W

Z

Y

The diodes works on

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A.C

D.C

both A and B

None of these

Resistance of 60 watt bulbs in 120V line is:

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20 ohms

240 ohms

0.15 ohms

180 ohms