An electron moving perpendicular to a uniform magnetic field of ...

[imanialler]

An electron moving perpendicular to a uniform magnetic field of 0.22 T moves in a circle with a speed of 1.5  107 m/s. What is the radius of the circle? (e = 1.60  10-19 C, melectron = 9.11  10-31kg)
 
  A) 1.5 mm
  B) 0.22 mm
  C) 2.2 mm
  D) 0.39 mm
  E) 3.9 mm

Question 2

When light of wavelength 350 nm is incident on a metal surface, the stopping potential of the photoelectrons is 0.500 V.
 
  What is the threshold (cutoff) frequency of this metal? (c = 3.00  108 m/s, h = 6.626  10-34 J  s, 1 eV = 1.60  10-19 J)
  A) 3.47  1014 Hz
  B) 3.74  1014 Hz
  C) 4.73  1014 Hz
  D) 7.36  1014 Hz

[cpetit11]

Answer to Question 1

E

Answer to Question 2

D