Question # 1

An organ pipe open at both ends and another organ pipe, closed at one end willresonate with each other, if their lengths are in ration of

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1:1

1:4

2:1

1:2

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

In a half wave rectifier circuit operating from 50 Hz mains frequency, the fundamental frequency in the ripple would be:

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25 Hz

70.7 Hz

50 Hz

100 Hz

In nuclear fission reaction, when the products are 140X and 94Sr, the number of neutrons emitted is

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1

2

5

9

A piece of Aluminium (Al) and a piece of Germanium (Ge) are cooled T1 K to T2 K. The resistance of:

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Each of them increases

Each of them decreases

Al increases and Ge decreases

Al decreases and that of Ge increases

The rate of change of momentum of a molecule is equal to:

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Pressure

Work

Density

Force

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

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Isochoric process

Isobaric process

Adiabatic process

Isothermal process

A motor boat is travelling with a speed of 3.0 m/sec. If the force on it due to water flow is 500 N, the power of the boat is

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150 KW

1.5 KW

heat energy

chemical energy

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

With the propagation of longitudinal waves through a material medium, the quantitiestransferred in the direction of propagation are:

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Energy, momentum and mass

Energy and momentum

Energy and mass

Energy

Which of the Following bulb will glow Brightest?

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100W

200W

300W

400W

In full wave rectification, the output DC voltage across the load is obtained for.

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The positive half cycle of input AC only

The negative half cycle of input AC

The completes cycle of input AC only

All of the above

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

The maximum kinetic energy of emitted photoelectrons depends upon:

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The intensity of incident light

Frequency of the incident light

Temperature of the surface

All of above

An electron and a proton are projected at right angles to a uniform magnetic field with

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the electron trajectory will be less curved than proton’s trajectory

the electron trajectory will be more curved than proton’s trajectory

) both trajectories will be equally curved

) both particles continue to move along a straight lins

Diffraction pattern has also been observed for:

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Proton

Neutron

Hydrogen atom

All of them

If a rotating body is moving counter clockwise, direction of angular velocity will be

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along linear velocity

towards the center

along the axis of rotation

away from center

At constant temperature, if the volume of a given mass of a gas is doubled, then the density of gas becomes:

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Double

Remains constant

Half

None of these

Monochromatic light of wavelength 300 nm is incident normally on a surface of area 4 cm2.

If the intensity of light is 150 mW/m2; the rate at which photon strike the surface:

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2.53 × 1019

7.5 × 1019

9.1 × 1013

2.53 × 1013

The fundamental frequency of a closed organ pope is 50 Hz. The frequency ofsecond over tone is

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100hz

150hz

60hz

250hz

Brownian motion confirms the truth of :

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Wave theory of light

Boyle's law

Kinetic theory of gases

Adiabatic process

Diesel engine coverts ____________ of available heat energy into work.

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20% to 25%

25% to 30%

30% to 35%

35% to 40%

In the theory of dimensional analysis, heat may be properly represented by:

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ML²T^-2

MT^-2

ML^-1T^-1

None of these

Photo cells are used for :

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Security and counting system

Automatic door system

Automatic street lighting

All of these

An electron in the n=1 orbit hydrogen atom is bound by 13.6 eV. If a hydrogen atom is in the n=3 state, how much energy is required to ionize it:

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13.6 eV

4.53 eV

3.4 eV

1.51eV

Capacitor stores energy in the form of :

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Electric field

Both of these

Magnetic field

Gravitational field

The shortest wavelength of X-rays emitted from an X-rays tube depends on the:

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Current in the tube

Voltage applied to the tube

Nature of gas in the tube

Nature of material of tube

In order to perform experiment, Davisson and Germer used accelerating voltage of:

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54V

120V

220V

400V

A photo cell receives light from a source at 50 cm away and produces 40mAcurrent inthe circuit. When the same source at is at distance 1 m from photo cell,current in the circuit will be

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20 mA

80mA

60 mA

10 mA

In a closed organ pipe, the fundamental frequency is f. What will be the ratio of thefrequencies of the next three overtones?

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2 : 3 : 4

3 : 7 : 11

3 : 4 : 5

3 : 5 : 7

A stone is thrown up from the surface of earth when it reaches at maximum height. its total energy is equal to

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mgh

1/2 𝑚𝑣²

zero

2mgh

The relationship between Boltzmann constant K with R and N_Ais given as:

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k = RN_A

k = R/N_A

k = NR/N_A

None of these

The energy stored in wound watch spring is

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K.E.

P.E.

heat energy

chemical energy

A wave which consists of a single, non-repetitive disturbance is called a

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Continuous wave

Longitudinal wave

Pulse

Transverse wave

Real gases strictly obey gas laws at:

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High pressures and low temperatures

Low pressures and high temperatures

High pressures and & temperatures

None of these

The rate of change of momentum of a body falling freely under gravity is equal to its

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Impulse

Kinetic energy

Pover

Weight

Resistance of 60 watt bulbs in 120V line is:

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20 ohms

240 ohms

0.15 ohms

180 ohms

select Which one of the following is not performing projectile motion

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A gas filled balloon

) Bullet fired from gun

A football kicked

A baseball shot

Figure represents a graph of kinetic energy (K) of the photoelectrons (in eV) and frequency (v) for a metal used as cathode in photoelectric experiment. The work function of metal is:

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1 eV

2 eV

1.5 eV

3 eV

As the working substance of a heat engine completes a cycle, there is no change in:

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Internal energy

Pressure

Volume

All of these

Light of frequency 4f0 is incident on the metal of the threshold frequency f0. The maximum kinetic energy of the emitted photoelectrons is

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3h f0

3/2h f0

2h f0

1/2h f0