Quiz 5 Solutions

Quiz 5 Solutions - Physics 1C Fall 2005 Quiz 5 Solutions...

This preview shows pages 1–2. Sign up to view the full content.

Physics 1C Fall 2005 Quiz 5 Solutions Version A 1. Blue light ( λ = 460 nm E=hf=2.7eV) is incident on a piece of potassium ( φ = 2.20 eV). What is the maximum kinetic energy of the ejected photoelectrons? ( h = 6.63 × 10 34 J s, c = 3.00 × 10 8 m/s, 1 eV = 1.60 × 10 19 J, and 1 nm = 10 9 m) a. 1.0 eV b. 0.50 eV c. 0.25 eV d. 4.9 eV Max KE electron is E(photon) – work function = 2.7 eV – 2.2 eV = 0.5 eV 2. What is the maximum velocity of a photoelectron emitted from a surface with work function 5.00 eV when illuminated by 200.0 nm ultraviolet light? ( m electron = 9.11 × 10 31 kg, h = 6.63 × 10 34 J s, 1 eV = 1.60 × 10 19 J, and 1 nm = 10 9 m) a. 800 000 m/s b. 653 000 m/s c. 431 000 m/s d. 212 000 m/s E(phot) = hc = 9.9 x 10 -19 J, Wk fn = 5 x 1.6 x 10 -19 J = 8 x 10 -19 J, max KE elec=(9.9-8.0) x 10 -19 J So ½ mv 2 = 1.9 x 10 -19 J, solve for v = 653000 m/s 3. Which change will not change the kinetic energy of the most energetic electrons emitted in the photoelectric effect? a. changing the brightness of the light b. changing the frequency of the light c. changing the metal the light is hitting d. all of the above will change the electron’s kinetic energy

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 04/17/2008 for the course PHYS 1C taught by Professor Smith during the Fall '07 term at UCSD.

Page1 / 2

Quiz 5 Solutions - Physics 1C Fall 2005 Quiz 5 Solutions...

This preview shows document pages 1 - 2. Sign up to view the full document.

View Full Document
Ask a homework question - tutors are online