Online Test

Question # 1

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

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Ultraviolet

Infra red

Visible

X-ray

In petrol engine, the second stroke is the

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Compression

In take

Power

None of these

A student finds the time period of a simple pendulum. Then he plot a graph between length and time period. The graph is a

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Straight line

Parabola

Ellipse

Circle

Energy can be stored in

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Magnetic field of a capacitor

Electric field of a capacitor

Dielectric

None of these

A forward biased p-n junction offers

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Zero resistance

Very high resistance

Few ohm resistance

None

Polaroids are used in

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Sun glasses

The production and analysis of plane polarized light

Stereoscopic motion picture

All of these

The electrons are emitted from the metal when light falls on it is of

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High frequency

Low frequency

Suitable frequency

None of these

Fractional error in a measured quantity is determined by

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Measured value / Absolute error

Absolute error / Measured value

Measured value + Absolute error

Measured value - Absolute error

Current through a metallic conductor is directly proportional to the potential difference applied across its ends, this is

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Ohm's law

Gauss's law

Faraday's law

none of them

Thermal radiations are a type of:

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Mechanical waves

Electromagnetic waves

Alpha rays

Electrons

The resistance of 20 cm long wire is 10 Ω when the length is changed to 40 cm.The new resistance is

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10 Ω

20 Ω

30 Ω

40 Ω

A phenomenon in which a low energy photon interact with metal and usually absorbed with the emission of an electron is known as

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Compton effect

Pair production

Photoelectric effect

None of these

Split rings are used in the device

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A.C. generator

A.C. motor

D.C. motor

All of them

Semiconductor materials have the conductivities generally lies between

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10^-5 to 10^-6 (Ωm)^-1

10^-6 to 10^-4 (Ωm)^-1

10^-7 to 10^-3 (Ωm)^-1

None of these

A choke coil is used as a resistance in

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d.c.circuit

a.c.circuit

d.c potentiometer circuit

Wheatstone bridge

Light emitting diode work when it is

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Forward biases

Reverse biased

Both

None of these

If the red light is replaced by blue light illuminating the object in a microscope the resolving power of the microscope

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Decreases

Increases

Gets halved

Remains unchanged

A frame of reference is any coordinate system to which measurements are taken as

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Correctly

Specifically

Relative

None of these

Pressure exerted by a gas on the walls of its container is due to

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Adhesion between the gas molecules and the container

Cohesion between the gas molecules and the container

Collision between the gas molecules and the container

Surface tension of the gas

In A.C. choke, the power consumption is

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Small

Very small

Extremely small

None of these

Which of the following diode is used to derive the current in external circuit when light is incident in the circuit

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photo diode

light emitting diode

photo voltaic cell

none of them

The appearance of colours in the shape (or oil) film results from:

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Dispersion

Interference

Reflection

Refraction

The charge moving perpendicular to the magnetic field 'B' with a certain velocity 'v' experiences

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No Force

Maximum Force

Minimum Force

None of these

The Weber is unit of measure of:

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Conductance

Electric current

Magnetic flux

Electric flux

In YDS experiment, condition for constructive interference is that path difference is equal to

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nλ

mλ

(n + 1/2)λ

(m + 1/2)λ

Thyroid cancer is cured by

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cesium-137

strontium-90

carbon-14

cobalt-60

RBE of Neutrons and protons below 10 MeV is

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0.5 RBE

10.0 RBE

0.8 RBE

1.7 RBE

Rate of change of momentum is called

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impulse

force

torque

momentum

If frequency of applied signal and time base generator are same the output signal will be

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Stationary

Over lapping

Both A and B

None of these

In photoelectric effect the energy of ejected electron depends on

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The frequency

The intensity

Both frequency and intensity

None of these

The torque produced in d.c. motor vanishes due to change of direction after each half revolution due to

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Reversed torque

Creates jerk

Both

None of these

Average value of A.C over a cycle is

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V_o

2V_o

V_osinθ

Zero

The temperature of the surface of sun is about

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5 million degree Celsius

10 million degree Celsius

15 million degree Celsius

20 million degree Celsius

The electromotive force is closely related to

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magnetic flux density

potential difference

electric field intensity

inductance

Wavelength of X-rays falling at glace angle 30° on crystal with atomic spacing 2 x 10^-9m for the first order diffraction is

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4 x 10^-6m

2 x 10^-10m

0.2 x 10^-10m

20 x 10^-10m

Polythene,polystyrene and nylon are example of

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Polymeric solids

Crystalline solids

Glassy solids

The energy stored in an inductor is

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Electrostatic

Electromagnetic

Magnetic

Mechanical

The nature of capacity of electrostatic capacitor depends on

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Shape

Size

Thickness of plates

Area

A sodium surface is illuminated with light of wavelength 300 nm. The work function of sodium metal is 2.46 eV. Find the electrons of maximum energy which

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3.12 eV

4.14 eV

4.63 eV

5.23 eV

The temperature at which the average K.E of a molecule of a gas will be the same as that of an electron accelerated through 1 volt will be

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7700 K

6700 K

8700 K

900 K

Do bends in a wire affect its electrical resistance

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Yes

No

Affects a little

None of these