Question # 1

A black body is

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an ideal absorber

an ideal radiator

both of them

none of them

There is no way to detect:

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Absolute uniform motion

Accelerated motion

State rest

State of motion

None of these

When a platinum wire is heated, it appears dull red at about

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500°C

900°C

1100°C

1300°C

Strictly speaking, the earth is:

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An accelerated frame of reference

A non-inertial frame of reference

An inertial frame of reference

^{A non-accelerated frame of reference}

Both (A) and (B)

In photoelectric effect the energy of ejected electrons depend on

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The frequency

The intensity

Both frequency and intensity

None of these

In order to produce pair production, a photon must have a energy

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0.511 Me v

0.256 Me v

1.02 Me v

0.956 Me v

The ratio of energy E to the corresponding frequency (f) of the radiation (emitted or absorbed) is called:

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Wien's constant

Stefen's constnat

Planck's constant

Boltzmann's constant

None of these

The inside cavity of the black body is

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painted white

painted silver

blackened with soot

painted red

If A represents linear momentum and c, the velocity of light, then unit of pc in international system of units is:

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Newton

Joule

Joule-Sec

Joule-s^-1

Watt

The nature of radiations emitted by a hot body depends upon its:

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Metarial

Temperature

colour

Volume

Length

The Nobel Prize on the explanation of photoelectric effect was awarded to:

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Max. Planck

Maxwell

Bohr

Rutherford

None of these

The location and speed anywhere on earth can now be determined using relativistic effects by NAVISTAR to an accuracy of

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2 cm/s

20 cm/s

200 cm/s

2000 cm/s

The value of the Stephen's constant for black body radiations is given by

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5.6 x 10⁸Wm^-2K^-4

5.67 x 10^-8Wm^-2K^-4

2.9 x 10^-3mK

2.9 x 10³mK

The way through which electromagnetic radiations or photons interact with matter depends upon their:

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Wavelength

Frequency

Energy

Temperature

All of these

When a position comes close to an electron they annihilate into

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one photon

two photons which travel in the same direction

two photons which travels in the opposite direction

two photons which travel in any direction

If a body reaches a speed equal to the speed of light, then its mass will became

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zero

very small

infinity

none of these

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ECAT Physics Chapter 19 Dawn of Modern Physics Online Test MCQs With Answers

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