A stopping potential of 0.50 V is required when a phototube is ...

[Garrulous]

A stopping potential of 0.50 V is required when a phototube is illuminated with monochromatic light of wavelength 590 nm.
 
  Monochromatic light of a different wavelength is now shown on the tube, and the stopping potential is measured to be 2.30 V. What is the wavelength of this new light? (c = 3.00  108 m/s, e = - 1.60  10-19 C, h = 6.626  10-34 J  s, 1 eV = 1.60  10-19 J)
  A) 320 nm
  B) 300 nm
  C) 340 nm
  D) 360 nm
  E) 410 nm

Question 2

As shown in the figure, a wire and a 10- resistor are used to form a circuit in the shape of a square, 20 cm by 20 cm.
 
  A uniform but nonsteady magnetic field is directed into the plane of the circuit. The magnitude of the magnetic field is decreased from 1.50 T to 0.50 T in a time interval of 63 ms. The average induced current and its direction through the resistor, in this time interval, are closest to
 
  A) 63 mA, from b to a.
  B) 38 mA, from b to a.
  C) 63 mA, from a to b.
  D) 38 mA, from a to b.
  E) 95 mA, from a to b.

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Answer to Question 1

A

Answer to Question 2

A

[Garrulous]

Excellent

[gcook]

TYSM