21.1 Planck and Quantum Nature of Light
Some television tubes are CRTs. They use an approximately 30-kV accelerating potential to send electrons to the screen, where the electrons stimulate phosphors to emit the light that forms the pictures we watch. Would you expect X-rays also to be created? Explain.
- No, because the full spectrum of EM radiation is not emitted at any temperature.
- No, because the full spectrum of EM radiation is not emitted at certain temperatures.
- Yes, because the full spectrum of EM radiation is emitted at any temperature.
- Yes, because the full spectrum of EM radiation is emitted at certain temperatures.
What is the accelerating voltage of an X-ray tube that produces X-rays with the shortest wavelength of 0.0103 nm?
- 1.21 × 1010 V
- 2.4 × 105 V
- 3.0 × 10−33 V
- 1.21 × 105 V
21.2 Einstein and the Photoelectric Effect
A 500 nm photon of light strikes a semi-conductive surface with a binding energy of 2 eV. With what velocity will an electron be emitted from the semi-conductive surface?
- 8.38 × 105 m/s
- 9.33 × 105 m/s
- 3 × 108 m/s
- 4.11 × 105 m/s
True or false—Treating food with ionizing radiation helps keep it from spoiling.
21.3 The Dual Nature of Light
Sunlight above the Earth’s atmosphere has an intensity of 1.30 kW/m2 . If this is reflected straight back from a mirror that has only a small recoil, the light’s momentum is exactly reversed, giving the mirror twice the incident momentum. If the mirror were attached to a solar sail craft, how fast would the craft be moving after 24 hr? Note—The average mass per square meter of the craft is 0.100 kg.
- 8.67 × 10−5 m/s2
- 8.67 × 10−6 m/s2
- 94.2 m/s
- 7.49 m/s
Consider the counter-clockwise motion of LightSail-1 around Earth. When will the satellite move the fastest?
- point A
- point B
- point C
- point D