Question # 1

Two electrons approach each other their relative velocity will be.

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Zero

c

c/2

Infinity

In the experiment of photo electric effect the minimum frequency of photons at which electrons are emitted from a metal surface is called.

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Critical frequency

Typical frequency

Threshold frequency

Surface frequency

The angular speed of an electron in the nth orbit of Bohr's hydrogen atom is.

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Directly proportional to n

Directly proportional to n2

Inversely proportional to n

Inversely proportional to n2

Which both elements are good for nuclear fission.

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Thorium an uranium

Thorium and radium

Plutonium and uranium

Plutonium and throrium

An operational amplifier can be used as a

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Comparator

Night switch

Inverting and non inverting amplifier

All of the above

If the base emitter junction is forward biased and base collector junction is reverse biased the BJT is in.

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cut of mode

Amplification mode

Saturation mode

Inversion mode

When we pass a radiation from a radioactive material through an electric field.

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All three kinds of rays will be deflected

Only the Gama rays are deflected

The Alpha and Beta particles are deflected

Only the alpha particles are deflected

The charge on a helium nucleus is equal to the charge of.

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Two electrons

Two protons

Two neutrons

One proton

The path of electron in Rutherford atomic model according to classical theory a.

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Parabolic

Straight line

Spiral

Circular

A photon is chasing an electron, whose speed is 0.9 c What is their relative speed.

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0.1 C

C

0.8 C

0.9 C

As the mass number varies, which of the quantities does not change w.r.t nucleus.

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Mass

Volume

Binding energy

Density

LED is a p-n junction that emits

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Visible light

X- rays

Ultraviolet light

electromagnetic waves

Transistor stands for

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Transfer of resistance

Transfer of current

Transfer of power

Transfer of voltage

The two elements with same number of electrons but different mass number are called.

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Isotones

Isobars

Isotopes

Isomers

Nuclear force exists between

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Proton proton

Neutron -neutron

neutron -proton

All of these

Mean life of a radioactive sample is 100 s its half life will be

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0.693 s

1 s

6.93 s

69.3 s

An increase in frequency above threshold frequency results in.

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Increase in photo electric current

Increase in K.E. of electrons

Decrease in photoelectric current

Decreases in K.E. of electrons

In an electronic transition atom cannot emit

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Gama rays

Visible rays

Infrared rays

Ultraviolet rays

On which factor cut off wavelength of X-rays coming from a Coolidge tube depends upon.

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Target material

Accelerating voltage

Filament temperature

Separation between target and the filament

When Photon incident on a metal produce the emission of electrons the process is called.

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Photo electric effect

Pair production

x-rays production

Gama ray production

A newly prepared radioactive nuclide has a decay constant Lamda of 10-6 s-1 What is the approximate half life of the nuclide.

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1 hour

1 day

1 week

1 month

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