Monochromatic light of frequency 6 . 0 × 10 14 Hz is produced by a laser. The power emitted is 2 . 0 × 10 - 3 W . What is the energy of a photon in the light beam?

Frequency of light ν = 6 . 0 × 10 14 Hz Power emitted P = 2 . 0 × 10 - 3 W Energy of photon E = h ν where, h = 6 . 63 × 10 - 34 Js is the plank constant ∴ E = h v = 6 . 63 × 10 - 34 Js × 2 . 0 × 10 14 Hz ⇒ E = 3 . 98 × 10 - 19 J

Monochromatic light of frequency 6 . 0 × 10 14 Hz is produced by a laser. The power emitted is 2 . 0 × 10 - 3 W . How many photons per second, on average, are emitted by the source?

Frequency of light ν = 6 . 0 × 10 14 Hz Power emitted P = 2 . 0 × 10 - 3 W Energy of photon E = h ν where, h = 6 . 63 × 10 - 34 Js is the plank constant ∴ E = h v = 6 . 63 × 10 - 34 Js × 2 . 0 × 10 14 Hz ⇒ E = 3 . 98 × 10 - 19 J Let the number of photons emitted by a source per second is n Then power emitted P = n E ⇒ 2 . 0 × 10 - 3 W = n × 3 . 98 × 10 - 19 J ⇒ n = 2 . 0 × 10 - 3 W 3 . 98 × 10 - 15 J ⇒ n = 5 . 0 × 10 15 photons per second

E M B I B E

NCERT Exemplar Physics - Class 12>Chapter 17 - Sample Paper II>SAMPLE PAPER>Q 11

MEDIUM

12th CBSE

IMPORTANT

Earn 100

Draw a circuit diagram of a potential divider using a cell and a rheostat. Also, mark the output terminals.

Important Questions on Sample Paper II

MEDIUM

12th CBSE

IMPORTANT

NCERT Exemplar Physics - Class 12>Chapter 17 - Sample Paper II>SAMPLE PAPER>Q 15

A plane electromagnetic wave of frequency

25 MHz

travels in free space along the

x -

direction. At a particular point in space and time.

E = 6.3 j V / m

. What is

B

at this point?

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12th CBSE

IMPORTANT

NCERT Exemplar Physics - Class 12>Chapter 17 - Sample Paper II>SAMPLE PAPER>Q 16

Define the power of a lens. Show that it is inversely proportional to the focal length of the lens.

HARD

12th CBSE

IMPORTANT

NCERT Exemplar Physics - Class 12>Chapter 17 - Sample Paper II>SAMPLE PAPER>Q 19

Draw a circuit for determining the internal resistance of a cell using a potentiometer. Explain the principle on which this method is based.

HARD

12th CBSE

IMPORTANT

NCERT Exemplar Physics - Class 12>Chapter 17 - Sample Paper II>SAMPLE PAPER>Q 20

What do you mean by diamagnetism, paramagnetism and ferromagnetism?

MEDIUM

12th CBSE

IMPORTANT

NCERT Exemplar Physics - Class 12>Chapter 17 - Sample Paper II>SAMPLE PAPER>Q 22

Monochromatic light of frequency $6.0 \times 10^{14} Hz$ is produced by a laser. The power emitted is $2.0 \times 10^{- 3} W$ . What is the energy of a photon in the light beam?

HARD

12th CBSE

IMPORTANT

NCERT Exemplar Physics - Class 12>Chapter 17 - Sample Paper II>SAMPLE PAPER>Q 22

Monochromatic light of frequency $6.0 \times 10^{14} Hz$ is produced by a laser. The power emitted is $2.0 \times 10^{- 3} W$ . How many photons per second, on average, are emitted by the source?