Question

1. What is the maximum frequency in 1018 Hz of photons produced in an CRT using a 20.65 kV accelerating potential, such as a color TV?

2. What is the maximum possible distance traveled in 14.2 μs by electrons ejected from a material by 77 nm photons, if they are bound to the material by 4.19 eV?

3. What is the wavelength of an electron moving at 3.27% of the speed of light? Give your answer in picometers.

4,What is the energy in 10-9 eV of a photon in a radio wave from an AM station that has a 1466 kHz broadcast frequency?

5. A physicist is watching a 10.4 kg orangutan at a zoo swing lazily in a tire at the end of a rope. He (the physicist) notices that each oscillation takes 4.15 s and hypothesizes that the energy is quantized. What is the difference in energy in 10-34 joules between allowed oscillator states?

Answer 1

1 )

using equation

f = E/ h

= qV/ h

= 1.6 X 10^-19 X 20.65 X 10³ / 6.67 X 10^-34

f = 5.006 X 10¹⁸ Hz

2 )

KE = h C / $\lambda$ - W

1/2 m v² = h C / $\lambda$ - W

= ( 6.67 X 10^-34 X 3 X 10⁸ / 1.6 X 10^-19 ) / 77 - 4.19

= ( 6.67 X 10^-34 X 3 X 10⁸ / 1.6 X 10^-19 ) / 77 - 4.19

= 1250/77 - 4.19

= 12.04 eV

v² = 2 X 12.04 X 1.6 X 10^-19 / 9.11 X 10^-31

v = 2.0565 X 10⁶ m/s

d = v X t

= 2.0565 X 10⁶ X 14.2 X 10^-6

d = 28.791 m

3 )

v = 3.27 %

= (3.27/100) X 3 X 10⁸

v = 9810000 m/s

$\lambda$ = h / m v

= 6.67 X 10^-34 / 9.1 X 10^-31 X 9810000

$\lambda$ = 7.4716 X 10^-11 m