📚 Topic Summary
In the photoelectric effect, when light shines on a metal surface, electrons can be emitted. The stopping potential is the voltage required to stop these emitted electrons from reaching a collector. Different frequencies (colors) of light have different energies; higher frequencies have more energy. When we measure the stopping potential for different light frequencies, we can learn about the relationship between light energy and electron kinetic energy, as described by Einstein's photoelectric equation: $E = hf = KE_{max} + W_0$, where $E$ is the photon energy, $h$ is Planck's constant, $f$ is the frequency of light, $KE_{max}$ is the maximum kinetic energy of the emitted electrons, and $W_0$ is the work function of the metal.
This experiment involves shining different frequencies of light onto a metal and measuring the stopping potential for each. By plotting the stopping potential against the frequency, we can determine Planck's constant and the work function of the metal.
🧪 Part A: Vocabulary
Match the terms with their definitions:
| Term |
Definition |
| 1. Photon |
A. The minimum energy required to remove an electron from a metal surface. |
| 2. Work Function |
B. The voltage required to stop the emitted electrons in the photoelectric effect. |
| 3. Stopping Potential |
C. A particle of light with energy $E = hf$. |
| 4. Frequency |
D. The number of waves that pass a fixed point in a unit of time. |
| 5. Planck's Constant |
E. A fundamental constant ($6.626 x 10^{-34} Js$) linking energy and frequency. |
✍️ Part B: Fill in the Blanks
The photoelectric effect demonstrates that light can behave as both a wave and a ________. When light of a certain ________ shines on a metal, ________ are emitted. The ________ potential is the voltage needed to stop these electrons. Einstein's equation relates the energy of light to the ________ energy of the emitted electrons and the ________ function of the metal.
🤔 Part C: Critical Thinking
Explain how increasing the intensity of light (while keeping the frequency constant) affects the stopping potential. Why?
