Threshold frequency for a metal is 1015 Hz. If light of wavelength 4000 overset texto mathop textA falls on its surface, then which of the following statement is correct?

Question

Threshold frequency for a metal is 1015 Hz. If light of wavelength 4000 overset texto mathop textA falls on its surface, then which of the following statement is correct? (A) Photo electrons come out with zero speed. (B) Photo electrons come out with 103 m/s speed. (C) Photo electrons come out with 105 m/s speed. (D) No photo electric emission takes place.

Tardigrade Admin · Accepted Answer

Wavelength of light, λ =4000 overset texto mathop textA Frequency of light v=(c/λ )=(3× 108/4000× 10-10)=0.75× 1015Hz Which is less than the given threshold frequency. Hence, no photoelectric emission takes place.

Q. Threshold frequency for a metal is 1015 Hz. If light of wavelength $4000 A o$ falls on its surface, then which of the following statement is correct?

Photo electrons come out with zero speed.

Photo electrons come out with $10^{3}$ m/s speed.

Photo electrons come out with $10^{5}$ m/s speed.

No photo electric emission takes place.

Wavelength of light, $λ = 4000 A o$ Frequency of light $v = \frac{c}{λ} = \frac{3 \times 10 ^{8}}{4000 \times 10 ^{- 10}} = 0.75 \times 10^{15} Hz$ Which is less than the given threshold frequency. Hence, no photoelectric emission takes place.

Q. Threshold frequency for a metal is 1015 Hz. If light of wavelength 4000Ao falls on its surface, then which of the following statement is correct?

Photo electrons come out with zero speed.

Photo electrons come out with 103 m/s speed.

Photo electrons come out with 105 m/s speed.

No photo electric emission takes place.

Wavelength of light, λ=4000Ao Frequency of light v=λc​=4000×10−103×108​=0.75×1015Hz Which is less than the given threshold frequency. Hence, no photoelectric emission takes place.

Q. Threshold frequency for a metal is 1015 Hz. If light of wavelength $4000 A o$ falls on its surface, then which of the following statement is correct?

Photo electrons come out with $10^{3}$ m/s speed.

Photo electrons come out with $10^{5}$ m/s speed.

Wavelength of light, $λ = 4000 A o$ Frequency of light $v = \frac{c}{λ} = \frac{3 \times 10 ^{8}}{4000 \times 10 ^{- 10}} = 0.75 \times 10^{15} Hz$ Which is less than the given threshold frequency. Hence, no photoelectric emission takes place.