Question # 1

For a normal AC cycle, during T/2 to T the diode act as:

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Open switch

full wave rectifier

Close switch

All are correct

Pressure may be defined as_____per second per unit area:

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Change in force

Change in momentum

Change in energy

Work done

The temperature scale approved in SI units is:

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Calslus scale

Kelvin scale

Fehrenhelt scale

None of these

In which region of the electromagnetic spectrum does the Lyman series of hydrogen atom lie?

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Infrared

Visible

Ultraviolet

X-rays

The frequency of the fundamental mode of open at one organ pipe is 400 Hz. Ifone end of pipe is closed the fundamental frequency will be

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800 Hz

600 Hz

400 Hz

200 Hz

Davisson and Germer, in their experiment used:

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Nickle crystal

Lead crystal

Graphite crystal

Glass

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

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

Two projectiles ‘A’ and ‘B’ are thrown with same speed but at angle of 40 degree and 50 degree with the horizontal. The horizontal range of ‘A’ will be:

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Equal to that of ‘B’

Greater than that of ‘B’

Less than that of ‘B’

4/5times that of ‘B’

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

A cell of negligible resistance and e.m.f 2 V is connected across a series combination of 2,3 and 5 ohms. The p.d. across the 3 Ω resistor is

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0.6 V

1/3 V

2/3 V

4/3 V

When the radioactive nucleus emits a beta particle, the proton neutron ration:

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increases by one

Remains same

Decreases by one

Decreases by four

A charge is 90C passes through a wire in 1 hour and 15 minutes. Wat is the current in the wire?

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10mA

20mA

15mA

25mA

If P is the pressure and V is the volume, Then PV will represent:

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Power

Work

Force

None of these

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

A body moving in a circular path with a constant speed has a

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Constant velocity

Constant kinetic energy

Constant acceleration

Constant displacement

The unit of work function is

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eV

Volt

Farad

Herdz

Magnetic field inside a solenoid is:

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) Directly proportional to current

Inversely proportional to current

Directly proportional to its length

Inversely proportional to total no of turns

The photoelectric effect was explained by:

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Einstein

Davison

Hertz

Planck

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

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

A particle revolves round a circular path with a constant speed. The accelerationof the particle is

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A. A long the circumference of the circle

Along the tangent

Along the radius

Zero

The body at rest may have:

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Energy

Momentum

Speed

Velocity

Davisson and Germer received the Nobel prize for their work on:

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Wave nature of particle

Corpuscular nature of wave

Dual nature of particle

All of them

In full wave rectification by bridge the number of diodes required are

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3

4

2

5

Two wires of same material have lengths L and 2L and cross-sectional area 4A and A respectively. the ratio of their specific resistance would be:

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1: 1

1: 8

8: 1

1: 2

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

Hotness and coldness of an object is represented in terms of:

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Heat

Temperature

Chemicial

None of these

The mud flies off the tyre of a fast moving car in the direction

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parallel to the moving tyre

anti parallel to the moving tyre

tangent to the moving tyre

none of these

Photo cells is a device which convert light into:

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Wave nature

Particle nature

Particle wave nature

Dual nature

The nature of thermal radiation is similar to:

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Ultraviolet rays

Light rays

Both of them

None of them

A circuit that converts Pulsating DC into smooth DC contain :

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Filter

Capacitor

Inductor

LC circuit

In photo electric cell, the photo electric current

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Decreases with increase in frequency of light

Depends on intensity and frequency of light

Does not depend upon the frequency of light and but depends upon intensity of light

Increases with increase in frequency of light

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 source of a magnetic field is:

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An isolated magnetic

A static electric charge

A moving electric charge

None of these

The nature of thermal radiation is smaller to:

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Ultraviolet rays

Light rays

Both of them

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

No entropy change is associated with:

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Isothermal

Adiabatic process

Isobaric process

None of them

What is the resultant force in the diagram shown?

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Zero

6N to left

6N to right

11N to right

The diodes works on

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A.C

D.C

both A and B

None of these

A body of mass m kg is lifted by a man to a height of one meter in 30 sec. Another man lifts the same mass to the same height in 60 sec. The work done by them are in the ratio

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1: 2

1: 1

2: 1

4: 1