Question # 1

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

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Nitrogen

Helium

Hydrogen

Neon

None of these

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

We can excite an atom by

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Bombardment of particles

Radiating photons

Providing potential difference

All answer are true

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

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Small

Greater

Equal

Sometimes

Selenium is:

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An insulator

A conductor

Both A and B

Excellent conductor

None of these

An compared to solid matter, a crack or an air bubble allows:

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Great amount of X-rays to pass

Smallast amount of X-rays to pass

Very samall amount of X-rays to pass

Any of these

None of these

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

The electric field lines start from:

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Positive charge

Negative charge

Either A and B

Neutron

An atom

Photons must have energy equal to

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ev

En

hf

None of these

The value of the metastable state for Neon is

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20.66eV

20.61eV

19.23eV

18.70eV

The process of formation of spectrum is called:

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Interference

Spectroscopy

Dispersion

Reflection

Botha (A) and (D)

By CAT scans, we can detect the density difference of the order of:

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1%

20%

30%

50%

70%

Laser is a beam of:

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Visible light

Infra red light

Ultra violet light

Violet light only

yellow light only

If the distance between two charges is doubled,the force between them will become:

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Double

Half

One third

One fourth

The results of spectra obtained by Balmer were expressed in 1896 by:

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Bohr

Rydberg

Planck

Rutherford

Coulomb

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