If the absorption of electromagnetic radiation by matter results in the emission of radiation of the same or longer wavelengths for a long time, the phenomenon is termed as which of the following?

If the absorption of electromagnetic radiation by matter results in the emission of radiation of the same or longer wavelengths for a long or a short time, the phenomenon is termed as which of the following?

A

Luminescence

B

Fluorescence

C

Phosphorescence

D

Spontaneous emission

If the absorption of electromagnetic radiation by matter results in the emission of radiation of the same or longer wavelengths for a short time, the phenomenon is termed as which of the following?

A

Luminescence

B

Fluorescence

C

Phosphorescence

D

Spontaneous emission

All the forms of matter except gases emit electromagnetic radiation continuously. The gases which electrically or thermally excited emit a certain wavelength only, then which of the following is/are true about the process (i) The spacing between the atoms in the other forms of matter is high than in gas (ii) The spacing between the atoms in gases is high than the other forms of matter (iii) The energy of the emitted radiation depends on the spacing between the atoms (iv) The wavelength of the emitted radiation depends on the spacing between the atoms

A

only i and iv

B

only i, iii & iv only

C

iv only

D

All the above

The moon looks blood red during a total lunar eclipse because some of the sunlight passes through Earth’s atmosphere to reach the moon. As the white light breaks up while passing through the atmosphere, most of its blue-colored wavelengths are absorbed and scattered. The remaining red wavelengths light up the moon in blood-red color. Which of the following statements do not support the assertion of the above-given statement? I: The moon looks blood red during a total lunar eclipse as the white light breaks up due to the Earth's atmosphere where most of its red-colored wavelengths are absorbed. II: The moon looks blood red during a total lunar eclipse as the earth blocks the white light to travel to the moon.

A

Only I

B

Only II

C

Either I or II

D

Both I and II

E

Neither I nor II

The sun emits a maximum amount of radiation at wavelengths near ____, while the earth emits maximum radiation near wavelengths of ____.

A

0.5 micrometers, 30 micrometers

B

0.5 micrometers, 10 micrometers

C

10 micrometers, 30 micrometers

D

1 micrometer, 10 micrometers

Consider the following statements in respect of a vapour-absorption refrigeration cycle: 1. The absorption refrigeration cycle is generally used when waste heat is a available from an existing source or when free energy like solar energy is to be used. 2. There are no moving parts in the absorption refrigeration plant except a small liquid pump. 3 the value of the coefficient of performance is nearly the same in both vapour-absorption and vapour-compression refrigeration plants. Which of the above statements are correct?

A

1, 2 and 3

B

1 and 2 only

C

1 and 3 only

D

2 and 3 only

To constitute a matter of res judicata which of the following conditions must concur?
1. The matter directly and substantially in issue in the subsequent suit or issue must be the same matter which was directly and substantially in issue either actually (section 11, explanation III) or constructively (section 11, explanation IV) in the former suit
2. The former suit must have been a suit between the same parties under whom they or any of them claim. Explanation VI of Section 11 must be read with this condition
3. The parties as aforesaid must have litigated under the same title in the former suit
4. The court which decided the former suit must have been a court competent to try the subsequent suit of the suit in which such issue has been subsequently raised. Explanation II of section 11 is to be read with condition
5. The matter directly and substantially in issue in the subsequent suit must have been heard and finally decided by the court in the first suit. Explanation V of section 11 is to be read with this condition

A

1, 2

B

3, 4

C

2, 4, 5

D

All of these

With reference to Visible Light Communication (VLC) technology, which of the following statements are correct? 1. VLC uses the electromagnetic spectrum wavelengths 375 to 780 nm. 2. VLC is known as long-range optical wireless communication. 3. VLC can transmit large amounts of data faster than Bluetooth. 4. VLC has no electromagnetic interference. Select the correct answer using the code given below:

A

1, 2 and 3 only

B

1, 2 and 4 only

C

1, 3 and 4 only

D

2, 3 and 4 only

An infinitely long wire carrying a current $$I\left( t \right) = {I_0}\cos \left( {\omega t} \right)$$ is placed at a distance a from a square loop of side a as shown in the figure. If the resistance of the loop is R, then the amplitude of the induced current in the loop is
Electromagnetic Theory mcq question image

Electromagnetic Theory mcq question image

A

$$\frac{{{\mu _0}}}{{2\pi }} \cdot \frac{{a{I_0}\omega }}{R}\ln 2$$

B

$$\frac{{{\mu _0}}}{\pi } \cdot \frac{{a{I_0}\omega }}{R}\ln 2$$

C

$$\frac{{2{\mu _0}}}{\pi } \cdot \frac{{a{I_0}\omega }}{R}\ln 2$$

D

$$\frac{{{\mu _0}}}{{2\pi }} \cdot \frac{{a{I_0}\omega }}{R}$$

Which is the longer: P is equal to Q, R is shorter than P, S is longer than R. T is longer than Q, is longer then S.

A

T

B

Q

C

S

D

P

If the absorption of electromagnetic radiation by matter results in the emission of radiation of the same or longer wavelengths for a long time, the phenomenon is termed as which of the following?

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