Two 5.0-C point charges are 12 cm apart. What is the electric ...

[Engineer]

Two 5.0-C point charges are 12 cm apart. What is the electric potential (relative to infinity) of this combination at the point where the electric field due to these charges is zero? (k = 1/40 = 9.0  109 N  m2/C2 )
 
  A) 25 MV B) 12.5 MV C) 1.5 MV D) 0.0 MV E) 0.75 MV

Question 2

A perfectly black sphere 18.0 cm in diameter is held at a temperature of 215C.
 
  ( = 5.670  10-8 W/m2  K4, Wien displacement law constant is 2.90  10-3 m  K, h = 6.626  10-34 J  s, c = 3.00  108 m/s)
  (a) Near what wavelength does this sphere radiate most strongly?
  (b) If all the radiated energy were at the wavelength found in part (a), how many photons would the sphere emit each second?

[dominiqueenicolee]

Answer to Question 1

C

Answer to Question 2

(a) 5.94 m (b) 9.79  1021 photons

[Engineer]

Excellent

[peter]

Gracias!