As the wavelength in increased form violet to red, the luminosity

Options

A. continously increases
B. continously decreases
C. increases then decreases
D. decreases then increases

Answer

To solve the question regarding how luminosity changes as the wavelength increases from violet to red, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Visible Spectrum**:
- The visible spectrum consists of seven colors, commonly remembered by the acronym VIBGYOR (Violet, Indigo, Blue, Green, Yellow, Orange, Red).
- The wavelengths of these colors range from approximately 350 nanometers (nm) for violet to about 700 nm for red.

2. **Identify Wavelength and Energy Relationship**:
- The energy of electromagnetic radiation is inversely proportional to its wavelength. This means that as the wavelength increases, the energy decreases.
- Mathematically, this can be expressed as:
\[ E = \frac{hc}{\lambda} \]
where \(E\) is energy, \(h\) is Planck's constant, \(c\) is the speed of light, and \(\lambda\) is the wavelength.

3. **Analyze Luminosity with Wavelength**:
- Luminosity refers to the total amount of energy emitted by a source per unit time. In the context of visible light, it can be understood as the brightness perceived by the human eye.
- A graph of relative luminosity versus wavelength typically shows that luminosity increases to a peak and then decreases as the wavelength continues to increase.

4. **Graphical Representation**:
- The graph of relative luminosity against wavelength starts low at violet (350 nm), rises to a peak around 555 nm (green light), and then decreases as the wavelength approaches red (700 nm).
- This indicates that luminosity is highest at around 555 nm and decreases for wavelengths longer than this.

5. **Conclusion**:
- Therefore, as the wavelength increases from violet to red, the luminosity first increases to a maximum at about 555 nm and then decreases thereafter.

### Final Answer:
As the wavelength increases from violet to red, the luminosity first increases and then decreases.