Question

Which figure shows the correct variation of applied potential difference (\(V\)) with photoelectric current (\(I\)) at two different intensities of light (\(I_1 < I_2\)) of same wavelengths:

• A.

  

• B.

  

• C.

  

• D.

  

Answer 1

The Correct Option is C

Photoelectric Effect and Current-Voltage Characteristics Explained:
The photoelectric current \( I \) is influenced by incident light intensity and applied potential difference \( V \).

Key observations include:
- For a constant frequency (or wavelength), the stopping potential \( V_0 \) is invariant, depending solely on incident light frequency, not intensity.
- Saturation current (peak current) is directly proportional to incident light intensity. Consequently, higher intensity light (e.g., \( I_2 \)) yields a greater saturation current than lower intensity light (e.g., \( I_1 \)).

Graph Selection Criteria:
Given the identical wavelength (or frequency) for both intensities, the stopping potential \( V_0 \) remains consistent for \( I_1 \) and \( I_2 \). However, due to \( I_2 > I_1 \), the saturation current for \( I_2 \) exceeds that for \( I_1 \).
Option (3) accurately depicts:
- Uniform stopping potential \( V_0 \) for both intensities.
- Saturation current for \( I_2 \) surpassing that for \( I_1 \), aligning with \( I_2 \)'s higher intensity.

Final Determination:
Option (3) is the correct graph, precisely illustrating the photoelectric current's behavior against applied potential for two distinct light intensities of the same wavelength.