Variation of photoelectric current with anode potential is shown below. Choose the correct option (V\(_0\) = stopping potential).
Show Hint
Saturation current depends on the \textbf{intensity} of incident light, while stopping potential depends on the \textbf{frequency} of incident light and the nature of the material. In the standard graph, always look for the intersection with the negative voltage axis at \(V_0\).
Step 1: Understanding the Question:
The goal is to identify the experimentally observed graph that correctly depicts the relationship between the photoelectric current and the potential applied to the collector (anode) plate. Step 3: Detailed Explanation:
In the photoelectric effect experiment:
1. Stopping Potential: When the anode is given a negative potential relative to the cathode, it repels photoelectrons. At a specific negative potential called the stopping potential (\(-V_0\)), even the electrons with the highest kinetic energy cannot reach the anode, and the current becomes zero.
2. Increasing Current: As the anode potential is increased (made less negative and then positive), more photoelectrons are able to reach the collector, resulting in an increase in the measured photoelectric current.
3. Saturation: At sufficiently high positive potentials, all the photoelectrons emitted from the cathode are collected by the anode. Beyond this point, increasing the potential does not increase the current further. this constant value is called the saturation current.
4. Graph Analysis: Graph-I correctly shows the current starting at zero for \(V = -V_0\), increasing as potential becomes positive, and eventually leveling off due to saturation. Graph-II is linear, Graph-III shows a decrease, and Graph-IV starts from the origin without showing a stopping potential; hence they are incorrect. Step 4: Final Answer:
The correctly shown variation is in Graph-I, which corresponds to option (1).
