Question # 1

In case of braking radiations, when the rate of deceleration is very large, the emitted radiation corresponds to:

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Short wavelength

Large wavelength

Very large wavelenth

Low frequency

Both (B) and (C)

The life time of metastable state is equal to

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Life time of excited state

Greater than by excited state

Zero

Less than by excited state

The range of wavelengths of colurs in the visible colours is

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140 nm to 456 nm

10 nm to 56 nm

410 nm to 656 nm

910 nm to 956 nm

None of these

Selenium is:

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An insulator

A conductor

Both A and B

Excellent conductor

None of these

Lyman series in the spectrum of hydrogen exists in the :

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Infra-red region

Visible region

Ultraviolet region

Both(A) and (B)

None of these

The He-Ne laser discharge tube is filled with:

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85% He

15% He

50% He

60% He

85% Ne

The minimum wavelength of X-rays produced of 1KV potential difference is applied across the anode and cathode of the tube is

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1.24 x 10^-10m

7.92 x 10^-20m

2.78 x 10^-14m

3.88 x 10^-11m

Gaussian surface is always:

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Rectangular

Spherical

Cylinder

Box shape

Any of these

The lasing or active medium in He-Ne laser discharge tube is:

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Nitrogen

Helium

Hydrogen

Neon

None of these

The first shell near the neucles is

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L-shell

X-shell

N-shell

M-shell

Spectrum represents the number of component colours present in certain light in terms of:

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Wavelength

Frequency

Energy

Both (A) and (B)

All of these

Tick the series which lie/s in. the infra-red region.

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Pfund series

Brackett series

Paschen series

All of these

None of these

X-rays produced in a tube operating at 10⁵V. The speed of X-rays produced is

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3 x 10⁸m/s

3.1 x 10⁸m/s

2.8 x 10⁸m/s

1.88 x 10⁸m/s

Energy required by an electron revolving in certain orbit to jump to an excited state is called:

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Ionization energy

Ionization potential

Excitation energy

Excitation potential

None of these

Static electricity is produced by the transfer of:

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Electrons

Protons

One fluid

Two fluid

None of these

A metastable stae:

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Is an excited state

Is that in which excited electron is stable

Is that in which excited electron is usually unstable

Means a time interval of 10^-8second

Both (A) and (C)

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