## Textbook 1B.15

$c=\lambda v$

derinceltik1K
Posts: 51
Joined: Sat Aug 17, 2019 12:15 am

### Textbook 1B.15

The velocity of an electron that is emitted from a metallic surface by a photon is 3.6 3 103 km?s2 1.
(a) What is the wavelength of the ejected electron?
(b) No electrons are emitted from the surface of the metal until the frequency of the radiation reaches 2.50 3 1016 Hz. How much energy is required to remove the electron from the metal surface?
(c) What is the wavelength of the radiation that caused photoejection of the electron?
(d) What kind of electromagnetic radiation was used?

Can someone explain how to solve "c"?

I got 1.66 x 10^-17 J for "B" but get get the answer for "C". Thank you!

Samuel Tzeng 1B
Posts: 103
Joined: Sat Aug 24, 2019 12:15 am

### Re: Textbook 1B.15

E(photon)=1.66*10^-17+KE(electron)= 1.66*10^-17J + 0.5 * (9.11*10^-31kg) * (3.6*10^6m/s)^2 = 2.25*10^-17J

then you can use the energy of the photon to find the wavelength using E=hv