Question

While studying the photoelectric effect, a chemist finds that light with the frequency of 5.6 x 10(14) Hz is insufficient to eject electrons from a metal surface. Which of the following might the chemist reasonably try if the goal is to eject electrons?

a. using light with frequency of 4.6 x 10(14) Hz

b. using light with frequency of 6.6 x 10(14) Hz

c. increasing the amplitude of the radiant light

d. decreasing the amplitude of the radiant light

What happens when an electron moves from shell 1 to shell 4 in a hydrogen atom?

a. a photon of light with wavelength of 97.23 nm is absorbed

b. a photon of light with wavelength of 97.23 nm is emitted

c. a photon of light with wavelength 6.856 x 10-4 nm is absorbed

d. a photon of light with wavelength 6.856 x 10-4 nm is emitted

Answer 1

1)

Since 5.6*10^14 Hz is not enough, it means that chemist should try higher frequency.

5.6*10^14 Hz must be less than cut off frequency

Answer: b

2)

Here photon will be captured and it will excite the atom

1/wavelength = -R* (1/nf^2 - 1/ni^2)

R is Rydberg constant. R = 1.097*10^7

1/wavelength = - R* (1/nf^2 - 1/ni^2)

1/wavelength = - 1.097*10^7* (1/4^2 - 1/1^2)

wavelength = 9.723*10^-8 m

wavelength = 97.23 nm

Answer: a