When a photoelectric surface is illuminated with light of ...

[audie]

When a photoelectric surface is illuminated with light of wavelength 437 nm, the stopping potential is measured to be 1.67 V.
 
  (1 eV = 1.60  10-19 J, e = 1.60  10-19 C, melectron = 9.11  10-31 kg, h = 6.626  10-34 J  s)
  (a) What is the work function of the metal, in eV?
  (b) What is the maximum speed of the ejected electrons?

Question 2

A tiny 0.0250-g oil drop containing 15 excess electrons is suspended between two horizontally closely-spaced metal plates that carry equal but opposite charges on their facing surfaces.
 
  The plates are both circular with a radius of 6.50 cm. (k = 1/40 = 9.0  109 N  m2/C2, e = 1.6  10-19 C)
  (a) How much excess charge must be on each plate to hold the oil drop steady?
  (b) Which plate must be positive, the upper one or the lower one?

[Cnarkel]

Answer to Question 1

(a) 1.17 eV (b) 7.66  105 m/s

Answer to Question 2

(a) 12.0 C (b) upper plate

[audie]

Both answers were spot on, thank you once again

[Cnarkel]

Great! Please up vote