Online Test

Question # 1

If the radioactive decay constant of radium is 1.07 x 10^-4 per year,then its half-life period is approx,equal to

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8,900 years

7,000 years

6,476 years

2,520 years

The amount of photoelectric current depends upon:

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Energy incident photons

Intensity of light beam

Both (A) and (B)

Magnitude of stopping potential

None of these

The oscillations produced by the factory floor by running heavy machinery is

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Free oscillations

Natural oscillations

Forced oscillations

None of these

A and B are the two inputs of a NOR gate. Its output would be 1 when

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A=0,,B=1

A=1,B=0

A=1,B=1

A=0,B=0

In scientific notation,0.0001 will be written as

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1 x 10⁴

1 x 10⁵

10⁴

10^-4

The magnitude of displacement is

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Distance between two points

Distance in a curved path

Shortest distance between two points

None of these

The speed of sound in hydrogen is

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two times its speed in oxygen

three times its speed in oxygen

four times its speed in oxygen

five times its speed in oxygen

The measure of the deformation in a solid when stress in applied to it is called

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elastic constant

Young's modulus

strain

elasticity

If two tuning forks are struck with one vibrating at 265 vib/sec and the other at 260 vib/sec, the resulting beat frequency is

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262.5 beats/sec

2.5 beats/sec

270 beats/sec

5 beats/sec

A driver in a lake wants to signal his distress to a person sitting on the edge of the lake flashing his water proof torch He should direct the beam

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Vertically up wards

Horizontally

At angle to the vertical which is slightly less than the critical angle

At an angle to the vertical which is slightly more than critical angle

α-particles is absorbed by

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1 mm sheet of copper

A paper

Lead sheet of 1 cm

None of these

The minimum distance between a source and the screen for which a real image is possible with a convex lens is

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Its focal length

Twice the focal length

Four times the focal length

Square of the focal length

The unit of focal power of a lens is

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Watt

Horse power

Dioptre

Kilo watt

An object thrown upward with an initial velocity at certain angle with the horizontal and moving freely under the action of gravity is called

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a rocket

an aeroplane

a projectile

a balloon

The travel time of light from Moon to Earth is

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2 min 10 sec

1 min

1 min 20 sec

3 min 30 sec

A motorist travels A to B at a speed at 40 km/h and returns at speed of 60 km/h.His average speed will be.

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40 km/h

48 km/h

50 km/h

60 km/h

Minimum energy required to take out the only one electron from ground state of He⁺ us

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13.6 eV

54.4 eV

27.2 eV

6.8 eV

A small amplitude progressive wave in a stretched string has a velocity of 10 m/s and a frequency of 100 Hz.The phase difference in radians between points 2.5 cm apart on the sting is

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π/2

π

π/4

Zero

The ultrasound used to monitor the blood flow, has apparent frequency after detection depends on the

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Velocity of the blood flow

Quantity of blood

Percentage of red cells

All of these

In metal detector, when a metal object is brought near the search coil, its inductance

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Decrease

Increases

Remains constant

None of these

Unit of universal gas constant is SI is:

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W K^-1 mol^-1

J/Nk^-1 mol^-1

Jk^-1 mol^-1

erg K^-1 mol^-1

In Bragg's formula, the path difference should beam integral multiple of the wavelengths

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d sin θ = nλ

d sin 2θ = nλ

2 d sin θ = nλ

None of these

The relation between emf and terminal potential difference is given by

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V_t = IR + I_r

E = V_t + I_r

E² = V_t + I_r

None of these

The time period of the seconds hand of watch is

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15 s

1 min

5 h

10 h

Certain charge +q is placed at the center of a sphere. At each patch of the sphere, the directions of electric intensity and vector area are:

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Same

Different

Opposite to each other

At 60^owith each other

Both (B) and (C)

When current passes through a solenoid coil, it behaves like a

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loop

circle

bar magnet

none of these

Paschen series lies in the region

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Ultraviolet

Infra-red

Visible

None of these

In this pressurized water reactor water is

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Prevent from boiling

Kept under high pressure

Hot water used to produce steam

All of these

Pressure exerted by a gas is

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Independent of density of the gas

Inversely proportional to the density of the gas

Directly proportional to the square of the density of the gas

Directly proportional to the density of the gas

In a simple harmonic motion (SHM).which of the following does not hold?

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The force on the particle is maximum at the ends

The acceleration is minimum at the mean position

The potential energy is maximum at the mean position

The kinetic energy is maximum at the mean position.

Energy stored per unit volume inside a solenoid is called

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Charge density

Volume charge density

Surface charge density

Energy density

The decrease in potential energy of a ball of mass 20 kg which falls from a height 50 cm is:

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968 J

98 J

1980 J

None of these

The typical example/examples of optically active crystals

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Quartz

Crystals of sodium chlorate

Crystals of sodium chloride

a and b

In Michelson interferometer if the moveable mirror is moved through a distance of 8λ then the number of fringes shifted are

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4

8

16

32

Basic part of parts of a heat engine

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Source

Sink

Working substance

All of these

A ball is thrown upwards with a velocity of 100 m/s.It will reach the ground after

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10 s

20 s

5 s

40 s

When the atomic particles are moving with velocities approaching that of light:

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Newton's laws become valid

Relativistic effects become prominent

Both A and B are valid

Neither A nor B

Their mass becomes zero

A wave travels in all directions from its source with a velocity depending upon the properties of

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Frequency

Medium

Wave length

None of these

If a wave can be polarized it must be

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An electromagnetic wave

A longitudinal wave

A progressive wave

A transverse wave

A proton and an α-particle are projected normally into a magnetic field.What will be the ratio of the radii of the trajectories of the proton and α particle?

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2 : 1

1 : 2

4 : 1

1 : 4

In flesh, light element like carbon, hydrogen and oxygen predominate. Three elements allows _______ amount of incident X-rays to pass through them

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Small

Greater

Equal

Sometimes