Question # 1

While dealing with the processes i thermodynamics, the working substances is usually:

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Oxygen gas

Hydrogen gas

Ideal gas

None of these

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

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Heat

Temperature

Chemicial

None of these

In order to increase the K.E of ejected photo electrons, there should be an increase in:

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Intensity of radiation

NoneI

Frequency of radiation

Both (b) & (c)

Work done in raising a box depends on:

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How fast it is raised

The strength of the man

The height by which it is raised

None of the above

A stone attached to one end of a string is revolved around a stick so that the string winds on the stick and gets shortened) What is conserved)

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angular momentum

kinetic energy

linear momentum

none of the above

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

A body moves a distance of 10 m along a straight line under the action of a force of 5 N. If the work done is 25 joules, the angle which the force makes with the direction of motion of the body is?

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0 Degree

30 Degree

60 Degree

90 Degree

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

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

A non-conducting semiconductor diode is:

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Forward biased

Poorly biased

Reverse biased

None of them

Resistance of 60 watt bulbs in 120V line is:

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20 ohms

240 ohms

0.15 ohms

180 ohms

The energy stored in wound watch spring is

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K.E.

P.E.

heat energy

chemical energy

Only those processes are probable to take place for which entropy os the system:

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Increases

Remains constant

Both A and B are correct

None of above

Brownian motion confirms the truth of :

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Wave theory of light

Boyle's law

Kinetic theory of gases

Adiabatic process

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

When resistances are connected in Parallel, the effective resistance will be

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Product of the reciprocals of the individual resistances

Product of the individual resistances

Sum of the reciprocals of the individual resistances

Sum of the individual resistances

The angular momentum changes form 2 units to 6 units in 4s. the torque is

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1 unit

3/2unit

1/2unit

4unit

The half-life of a certain element is 3.5 days at STP. If the temperature is doubled and pressure is reduced to half then half-life of the same element will be:

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1.75 days

3.5 days

7 days

14 days

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

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

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

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Infrared

Visible

Ultraviolet

X-rays

When temperature increases, frequency of organ pipe:

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Decreases

Remains the same

Increases

Becomes zero

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

The energy of photon of wavelength 1240 nm is:

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0.5 eV

1.0 eV

1.5 eV

2.0 eV

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

The temperature at which all the gases become liquid is called:

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273 K

-273 K

Absolute Zero

Both (B) and (C)

In case of planets the necessary acceleration is provided by

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Gravitational force

coulomb force

frictional force

centripetal force

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

Two bodies moving towards each other collide and move away in opposite directions. There is some rise in temperature of bodies because a part of the kinetic energy is converted into

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heat energy

electrical energy

nuclear energy

mechanical energy

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

If the range of a projectile is R, the potential energy will be maximum after the projectile has covered (from start) distance equal to:

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R/2

R/4

R

R/9

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 pulsating DC can be converted into constant voltage by using

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Filter

Full wave rectifier

Half wave rectifie

Bridge rectifier

The magnetic field produced due to the current in a straight wire is proportionalto the :

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Electric current

Conducting material

Length of the wire

Diameter of the wire

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

The diode charactristics curve is plot between

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I & t

V& t

V& I

None

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

A diode characteristics curve is a graph plotted between;

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Current and time

Voltage and time

Voltage and current

Forward voltage and reverse current

For X-rays which of the following is not correct:

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Cause of ionization in air when they pass through it

Can be deflected by electric and magnetic fields

Can be used to detect flaws in metal casting

Travel with the speed of light

A process which is carried at constant temperature and Boyle's law can be applied is called:

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Adiabatic process

Isothermal process

Isochoric process

None of these

Work function of all metals varies from 2 eV to 4eV. It is 4.2 eV for Aluminum and2eV for Sodium. If these two metals are illuminated by same light, the thresholdfrequency ofAluminum is

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Less than Sodium

Equal to that of Sodium

Grater than Sodium

Can’t be decided