Author Question: A stopping potential of 0.50 V is required when a phototube is illuminated with monochromatic light ... (Read 68 times)

Garrulous · **on:** Jul 29, 2018

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.