Quiz Chapter 7: Quantum Physics

1. Calculate the energy of a single photon of blue light with a frequency of 6.0 × 10¹⁴ Hz. (Planck's constant h = 6.63 × 10⁻³⁴ J s)

1. 3.98 × 10⁻¹⁹ J
2. 1.11 × 10⁻⁴⁷ J
3. 3.98 × 10⁻²⁷ J
4. 1.80 × 10⁻¹⁹ J

2. What is the gradient of a K_max against frequency (f) graph for any photoelectric metal surface?

1. Work function (Φ)
2. Planck's constant (h)
3. Threshold frequency (f₀)
4. Electron mass (m_e)

3. What happens to the energy of a photon when its wavelength increases?

1. Increases proportionally
2. Decreases because energy is inversely proportional to wavelength
3. Remains unchanged
4. Doubles automatically

4. According to Louis de Broglie, which physical property determines the de Broglie wavelength of a moving particle?

1. Its electric charge
2. Its momentum (p = mv)
3. Its surface area
4. Its temperature

5. An electron microscope offers significantly higher magnification and resolution than an optical light microscope because:

1. Electrons have much shorter de Broglie wavelengths than visible light wavelengths
2. Electrons travel at the speed of sound
3. Electrons carry a positive charge that absorbs optical distortions
4. Electrons expand glass lenses

6. Calculate the de Broglie wavelength of an electron moving at a velocity of 2.0 × 10⁶ m s⁻¹. (m_e = 9.1 × 10⁻³¹ kg, h = 6.63 × 10⁻³⁴ J s)

1. 3.64 × 10⁻¹⁰ m
2. 1.82 × 10⁻²⁴ m
3. 3.64 × 10⁻³⁴ m
4. 7.28 × 10⁻¹⁰ m

7. If the stopping potential for photoelectrons emitted from a metal plate is 2.0 V, what is the maximum velocity of the photoelectrons? (m_e = 9.1 × 10⁻³¹ kg, e = 1.6 × 10⁻¹⁹ C)

1. 8.39 × 10⁵ m s⁻¹
2. 7.04 × 10¹¹ m s⁻¹
3. 3.51 × 10⁵ m s⁻¹
4. 1.20 × 10⁶ m s⁻¹

8. A light source emits photons with a wavelength of 400 nm. What is the momentum of each photon? (h = 6.63 × 10⁻³⁴ J s)

1. 1.66 × 10⁻²⁷ kg m s⁻¹
2. 2.65 × 10⁻⁴⁰ kg m s⁻¹
3. 1.66 × 10⁻²⁹ kg m s⁻¹
4. 6.63 × 10⁻²⁷ kg m s⁻¹

9. What factor determines the MAXIMUM KINETIC ENERGY of photoelectrons emitted from a metal surface?

1. Intensity of the incident light
2. Frequency of the incident light
3. Surface area of the illuminated metal plate
4. Duration of light exposure

10. If light of frequency f below the threshold frequency (f < f₀) shines on a metal surface, what happens?

1. Photoelectrons are emitted very slowly after a long time delay
2. No photoelectrons are emitted regardless of light intensity
3. Photoelectrons are emitted with maximum kinetic energy
4. The metal surface instantly melts