Question

# 1. Why might a stream of red photons not cause an electron to be emitted from...

1. Why might a stream of red photons not cause an electron to be emitted from a gold surface?

A. The stream of red photons might not be hitting the surface with enough total energy per second

B. An electron absorbs the energy of one photon, and the red photon has too small of a wavelength to deliver enough energy.

C. An electron absorbs the energy of one photon, and the red photon has too small of a frequency to deliver enough energy.

D. The "work function" of gold is too small for the electron to be emitted.

2. Classical wave theory predicts that blackbody emitters should emit light with

A. more energy at low frequencies.

B. more energy at high frequencies.

C. roughly the same energy at all frequencies.

3. It is observed that the peak intensity for light emission by a blackbody is at

A. higher frequencies for higher temperature blackbodies.

B. higher frequencies for lower temperature blackbodies.

C. the same frequency for all temperature blackbodies.

4. Planck solved the blackbody emission problem by assuming that

A. light is emitted as a wave with very specific energy.

B. light is emitted as a photon, with energy determined by its frequency.

C. light is emitted as a photon, and all photons have the same energy.

5. When visible light is scattered from electrons in a gas, why do we not usually notice a change in the wavelength of the scattered light?

A. The wavelength doesn't actually always change.

B. The change in wavelength is hidden by all the different frequencies of light that get scattered.

C. The wave nature of light ensures that the wavelength does not change in scattering.

D. The photon nature of light does cause a change, but it is only a small change when compared to the wavelength of visible light.

6. In which situation would it be easiest to detect the Compton effect?

A. Smaller wavelengths of light scattering from smaller particles.

B. Smaller wavelengths of light scattering from larger particles.

C. Larger wavelengths of light scattering from smaller particles.

D. Larger wavelengths of light scattering from larger particles.

Q1. option C is correct . this problem is based on photoelectric effect which tells frequency should be a greater than a minimum sufficient energy.

Q2. option B is correct . this problem is based on ultraviolet catastrophe which is solved by planck by introducing planck's constant.

Q3. option A is correct . this problem is based on wein displacement law according to which

wavelength× temperature = constant

Q4. option B is correct . Planck introduced formula Energy = h×f

where f is frequency and h is planck constant.

Q5. option D seems most appropriate.

Q6. smaller particle cause large change in Compton wavelength so option c seems most appropriate.

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