A girl is performing a photoelectric experiment but no photoelectrons are being ejected. To eject electrons, she should change the light by

Options

A. Decreasing the frequency
B. Increasing the frequency
C. Increasing the intensity
D. Increasing the wavelength

Answer

To solve the problem of why no photoelectrons are being ejected in the photoelectric experiment, we need to understand the relationship between the energy of the incident light and the work function of the material. Here’s a step-by-step solution:

### Step 1: Understand the Photoelectric Effect
The photoelectric effect occurs when light of sufficient energy strikes a material and ejects electrons. The energy of the incident light is given by the equation:
\[ E = h\nu \]
where \( E \) is the energy, \( h \) is Planck's constant, and \( \nu \) is the frequency of the light.

### Step 2: Identify the Work Function
Each material has a characteristic work function (\( \phi_0 \)), which is the minimum energy required to eject an electron from the surface of the material. For photoelectrons to be emitted, the energy of the incoming light must be greater than the work function:
\[ h\nu > \phi_0 \]

### Step 3: Analyze the Situation
In the given scenario, the girl is performing the photoelectric experiment but no photoelectrons are being ejected. This indicates that the energy of the incident light (i.e., \( h\nu \)) is less than the work function (\( \phi_0 \)):
\[ h\nu < \phi_0 \]

### Step 4: Change the Light
To ensure that photoelectrons are ejected, the girl must change the light in such a way that the energy exceeds the work function. This can be achieved by:

- **Increasing the frequency of the light**: Since energy is directly proportional to frequency, increasing the frequency will increase the energy of the photons. Therefore, the correct action is to increase the frequency of the incident light.

### Conclusion
To eject photoelectrons, the girl should change the light by **increasing the frequency** of the light source.

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