Question

To have a larger photo current, which of the following should occur? (Select all the changes that apply.) a) brighter light. c) higher frequency b) dimmer light d) lower frequency

Short answer

Answer: a) brighter light, c) higher frequency

Step-by-step solution

Answer Choices

Here are the answer choices: a) brighter light b) dimmer light c) higher frequency d) lower frequency

Intensity and Photoelectron Emission

Brighter light means higher intensity, which corresponds to more photons hitting the photocathode material. More photons would cause the release of a larger number of photoelectrons and, consequently, a larger photo current. Thus, a brighter light (option a) would lead to a larger photo current. On the other hand, dimmer light (option b) would have the opposite effect, as it corresponds to a lower intensity, reducing the number of emitted photoelectrons and the photo current.

Frequency and Energy of Photons

The energy of a photon is directly proportional to its frequency, as described by the formula E = hf, where E is the energy, h is Planck's constant, and f is the frequency. A higher frequency (option c) means more energy, which can result in more photoelectrons being emitted, thus increasing the photo current. A lower frequency (option d), however, means less energy per photon. If the frequency is below the threshold frequency, no photoelectrons will be emitted, resulting in no photo current.

Conclusion

Based on the analysis of the photoelectric effect, to have a larger photo current, the following changes should occur: a) brighter light c) higher frequency