A photo-cell employs photoelectric effect toconvert [2006]a)change in the intensity of illumination intoa change in photoelectric currentb)change in the intensity of illumination intoa change in the work function of thephotocathodec)change in the frequency of light into achange in the electric currentd)change in the frequency of light into achange in electric voltageCorrect answer is option 'A'. Can you explain this answer?

Question

A photo-cell employs photoelectric effect toconvert   [2006]a)change in the intensity of illumination intoa change in photoelectric currentb)change in the intensity of illumination intoa change in the work function of thephotocathodec)change in the frequency of light into achange in the electric currentd)change in the frequency of light into achange in electric voltageCorrect answer is option 'A'. Can you explain this answer?

Answer

The photoelectric current is directly proportional to the intensity of illumination. Therefore a change in the intensity of the incident radiation will change the photocurrent also.

Answer

Answer:

To understand why the correct answer is option 'A', let's first discuss the photoelectric effect and how it is related to a photo-cell.

Photoelectric Effect:
The photoelectric effect is the phenomenon where electrons are emitted from a metal surface when it is exposed to light of a certain frequency or higher. This effect can be explained by considering light as composed of particles called photons. When a photon strikes the metal surface, it transfers its energy to an electron, allowing it to overcome the attractive forces of the metal and be emitted as a photoelectron.

Photoelectric Current:
The photoelectric current is the flow of electrons that occurs when light strikes a metal surface and causes the emission of photoelectrons. The intensity of illumination refers to the amount of light falling on the photo-cell per unit area per unit time. When the intensity of illumination increases, more photons strike the metal surface, resulting in a greater number of photoelectrons being emitted. This leads to an increase in the photoelectric current.

Explanation:
The photo-cell, which employs the photoelectric effect, uses a metal surface called the photocathode to generate photoelectrons. The intensity of illumination falling on the photocathode determines the number of photons striking it. This, in turn, affects the number of photoelectrons emitted and, ultimately, the photoelectric current.

Option 'A' is the correct answer because it states that a photo-cell converts a change in the intensity of illumination into a change in the photoelectric current. As the intensity of illumination increases, more photons strike the photocathode, resulting in a higher photoelectric current. Conversely, if the intensity of illumination decreases, fewer photons strike the photocathode, leading to a lower photoelectric current.

The other options are incorrect because they do not accurately describe the relationship between the photoelectric effect and the photo-cell. For example, option 'B' suggests that the intensity of illumination affects the work function of the photocathode, which is not true. Option 'C' suggests that the frequency of light is directly converted into an electric current, which is not accurate. Option 'D' implies that the frequency of light is directly converted into an electric voltage, which is also incorrect.

In summary, a photo-cell employs the photoelectric effect to convert a change in the intensity of illumination into a change in the photoelectric current.

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