Question # 1

Velocity of sound in air at a given temperature

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Increases with increase in pressure

Is independent of the pressure

Decreases with increases in density

Increases with increase in density

If an elevator is moving vertically up with an acceleration 'a' the force exerted on the floor by a passing of mass 'm' is

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Ma

Mg

M(g +a)

M (g-a)

Who designed the atomic reactor.

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Wilson

Rutherford

Teller

Fermi

The speed of bodies exceeding the speed of sound is called.

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Superesonic

Ultrasonic

Infrasonic

Super fast

For an electron or position the rest mass energy is equal to.

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0.21 MeV

0.51 MeV

1.51 MeV

1.21 MeV

A forward based p-n semiconductor diode is called.

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Photodiode

Photovoltaic cell

Amplifier

Ligh emitted diode

A wave source of frequency 1000 Hz emits waves of wavelength 0.1 m How long does is take for the waves to travel 2500 m.

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20 s

25 s

40 s

100 s

If temperature of the sink is decreased the efficiency of a Carnot engine

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Increases

Decreases

Remains constant

First increases and thend ecreases

Where is the velocity of electrons maximum in a diode.

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Near the cathode

Near the anode

In the space ini between the two elecrode.

It is same throughout the tube

What is the direction of the magnetic field lines inside a bar magnet.

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From north pole to south pole

From south pole to north pole

From side to side

There are no magnetic field lines

Which of the following is the magnitude of the gravitational force and is not the inherent property of the body.

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Mass

Weight

Speed

Length

Law of increase of entropy is a result of

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First law of thermodynamics

Second law of thermodynamics

Third law of thermodynamics

Zeroth law of thermodynamics

A double convex air bubble in water will behave as.

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Plane slab

Concave mirror

Convex lens

Concave lens

Which one of the following does not have the same dimenstions.

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Energy ,work, heat

Pressure, stress, Young's modulus

Voltage, electromotive force, potential difference

Electric flux, electric field, electric dipole moment

For an A.C. circuit the power factor is

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Always les than one

Always greater than one

Always equal to one

Absent

Ashes from a campfire deep in a cave show carbon -14 activity of only one eighth the activity of fresh wood. How long ago was that campfire made.

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13590 years

15190 years

17190 years

21190 years

Tracer techniques make use of.

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Neutron scattering

Electron beams

LASER

Radioactive isotopes

Which given element has lowest work function

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Na

Al

si

C

A spring obeying Hooke's law has an upstretched length 50 mm and a spring constant of 400 N m-1 What is the tension in the spriing when its overall length is 70 mm.

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8 N

28 N

160 N

400 N

Who invented commutator.

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William Sturgeon

William Smith

Michael Faraday

Mosely

The mains frequency in Pakistan is

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20 Hz

50 Hz

40 Hz

60 Hz

Sounds of frequencies higher than 20,000 Hz are called.

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Super sonics

Infrasonic

Ultrasounds

Audible sound waves

A frictionless heat engine can be 100% efficient only if its exhaust temperature is

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Equal to the input temperature

Less than the input temperature

0 ^oC

0 K

What is the power factors of wattles current.

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Infinity

Unity

0.5

Zero

The conductivity of a conductor is independent of the

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Electric charge

Electric potential

Electric field

Internal resistance

The maximum field that a dielectric material can with stand whiteout breaking down is called its.

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Di electric strength

Magnetic strength

Capacity

Resistance

On which of the following parameters capacitance does not depend upon.

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Area of the plates

Medium between the plates

Distance between the plates

Nature of material for plates

To which law of thermodynamics, the concept of temperature is related to.

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Zeroth law

First law

Second law

Third law

Why a positive charged object is made neutral by someone touching it.

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Electrons flow from the object

Proton flow onto the object

Protons flow from the object

Proton flow onto the object

If the presence of air friction, the path of a projectile appears as.

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Straight line

Parabola

Hyperbola

zig zag

One particle having zero mass and zero charge is.

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Positron

Electron

Neutrino

Neutron

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