Hey I stumbled upon these questions. Please help!

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JasonNovik3A
Posts: 21
Joined: Fri Sep 29, 2017 7:07 am

Hey I stumbled upon these questions. Please help!

Postby JasonNovik3A » Mon Oct 16, 2017 7:38 pm

21. What was the surprising outcome of the initial photoelectric experiments?

A. If electrons were ejected decreasing the light intensity resulted in no ejected electrons.

B. If electrons were ejected increasing the light intensity resulted in no ejected electrons.

C. If no electrons were ejected decreasing the light intensity resulted in ejected electrons.

D. If no electrons were ejected increasing the light intensity still resulted in no ejected electrons.

E. None of the above
0/1 point

22. If no electrons are ejected what experimental change is needed?

A. Use shorter wavelength or higher frequency light.

B. Use shorter wavelength or lower frequency light.

C. Use longer wavelength or higher frequency light.

D. Use longer wavelength or lower frequency light.

E. None of the above
0/1 point
Page 8/15

23. To interpret the results of photoelectric experiments the model of light needs to change from a ________ model to a ________ model. What are the two missing words?

A. particle, wave

B. particle, interaction

C. wave, particle

D. wave, photon

E. None of the above
0/1 point

24. In photoelectric experiments, typically what part of the electromagnetic spectrum is the incoming light?

A. Ultraviolet

B. Infrared

C. Visible light

D. Gamma rays

E. None of the above


Can ya'll give me the answers to these and explain please?

K Stefanescu 2I
Posts: 68
Joined: Fri Sep 29, 2017 7:04 am

Re: Hey I stumbled upon these questions. Please help!

Postby K Stefanescu 2I » Mon Oct 16, 2017 9:13 pm

23. C- photons must change to from a wave model to a particle model.
If they had been consistent with waves, increasing the intensity (I) would have caused more electrons to be emitted from the metal, given that I is proportional to A^2 (amplitude squared). However, despite increasing the intensity of the light, no more electrons were emitted. The energy of EACH photon needed to be large enough to cause an electron to be emitted. So, photons were functioning as particles.

Nancy Dinh 2J
Posts: 59
Joined: Fri Sep 29, 2017 7:07 am

Re: Hey I stumbled upon these questions. Please help!

Postby Nancy Dinh 2J » Mon Oct 16, 2017 9:29 pm

21. According to the wave model, a greater intensity would result in more energy, but this still did not eject the electrons. This was surprising because it meant stripping the wave model and viewing the rays as photons, which requires you to increase the frequency/decrease the wavelength to increase the energy. The answer is D.

Hope this helps!

Dylan Mai 1D
Posts: 70
Joined: Sat Jul 22, 2017 3:00 am

Re: Hey I stumbled upon these questions. Please help!

Postby Dylan Mai 1D » Mon Oct 16, 2017 11:39 pm

I believe 22 is A. If no electrons are ejected than that means there is not enough energy to eject the electron. To increase the energy, using a shorter wavelength/ higher frequency would increase the energy and potentially gain enough energy to eject an electron. E=hv, so with a higher frequency comes more energy.

Dylan Mai 1D
Posts: 70
Joined: Sat Jul 22, 2017 3:00 am

Re: Hey I stumbled upon these questions. Please help!

Postby Dylan Mai 1D » Mon Oct 16, 2017 11:40 pm

24 is A, Ultraviolet. I think I got this from my notes or one of the videos, but it also makes sense to have UV light be commonly used since it may have a better chance at ejecting electrons with its higher energy.


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