A 100-watt bulb emits monochromatic light of wavelength 400 nm. The number of photons emitted per second by the bulb is-

1. 40.12 × 1020 s-1

2. 2.012 × 1021 s-1

3. 2.012 × 1020 s-1

4. 20.12 × 1021 s-1

Subtopic:  Photo Electric Effect |
 77%
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When electromagnetic radiation of wavelength 300 nm falls on the surface of sodium, electrons are emitted with a kinetic energy of 1.68 ×105 J mol–1. The minimum energy needed to remove an electron from sodium and the maximum wavelength that will cause a photoelectron to be emitted are respectively-

1. 2.31 × 105 J mol–1, 517 nm

2. 23.1 × 105 J mol–1, 517 nm

3. 3.31 × 105 J mol–1, 417 nm

4. 33.1 × 105 J mol–1, 417 nm

Subtopic:  Photo Electric Effect |
 55%
From NCERT
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The threshold frequency νo for a metal is 7.0 ×1014 s–1. The kinetic energy of an electron emitted when radiation of frequency ν =1.0 ×1015 s–1 hits the metal, is-

1. 19.88 ×10–19 J

2. 1.988 ×10–19 J

3. 1.988 ×10–20 J

4. 19.88 ×10–17 J

Subtopic:  Photo Electric Effect |
 74%
From NCERT
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