# Photoelectric Detector and Energy Measurements

1. Apr 14, 2014

### bravellama

1. The problem statement, all variables and given/known data

Which of the following best summarizes how a photoelectric detector provides an energy measurement:

Answer choices:

A) As light of multiple colors falls on the detector, the detector measures the energy of just one frequency of light by having a hole of only one wavelength to let light in. We measure the size of the hole, and infer the energy, with a multimeter.

B) As light of one color falls on the detector, it changes the temperature of the detector. We measure the temperature of the detector, and infer the energy, with a multimeter.

C) As light of one color falls on the detector, the detector measures the frequency of the light by looking at how fast the electric field oscillates. We measure the frequency, and infer the energy, with a multimeter.

D) As light of one color falls on the detector, it ejects electrons that charge a capacitor. We measure the voltage of the capacitor, and infer the energy, with a multimeter.

E) There is no way to measure or infer energy of light with the photoelectric device. The device generates the light that we measure the energy of. The multimeter directly reads energy of the light.

F) As light of multiple colors falls on the detector, the detector looks at the correlation between the colors. We measure that correlation, and infer an energy, with a multimeter.

2. Relevant equations

hf = KE + work function

3. The attempt at a solution

I thought the answer was D, but now I am not so sure since the other answers are unclear. However, I don't think temperature has anything to do with it. Any advice would be great :) Thanks.

2. Apr 14, 2014

### Staff: Mentor

All other answers are so far off that they look confusing. D is right.

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