Temperature of the star is determined by

Options

A. distance
B. colour
C. size
D. none of these

Explanation

To determine the temperature of a star, we can utilize Wien's Displacement Law, which relates the temperature of an object to the wavelength at which it emits radiation most intensely. Here’s a step-by-step solution to the question:

### Step-by-Step Solution:

1. **Understand Wien's Displacement Law**:
- According to Wien's Displacement Law, the wavelength of light emitted at maximum intensity (λ_max) is inversely proportional to the temperature (T) of the black body. The law can be expressed mathematically as:
\[ \lambda_{max} \cdot T = b \]
where \( b \) is a constant.

2. **Identify the Variables**:
- In this equation, \( \lambda_{max} \) is the wavelength at which the star emits the most radiation, and \( T \) is the temperature of the star.

3. **Determine the Temperature**:
- By measuring the wavelength of the light emitted by the star, we can rearrange the equation to solve for temperature:
\[ T = \frac{b}{\lambda_{max}} \]
- This means that if we know the wavelength of the light that is emitted most intensely, we can calculate the temperature of the star.

4. **Relate Wavelength to Color**:
- The color of the light emitted by the star is directly related to its temperature. For example:
- A star that appears red has a lower temperature (less than 3000 K).
- A star that appears blue has a higher temperature (greater than 3000 K).
- Therefore, the color of the star can be used as an indicator of its temperature.

5. **Conclusion**:
- From the options given:
- A) Distance
- B) Color
- C) Size
- D) None of these
- The correct answer is **B) Color**, as it is through the color of the star that we can determine its temperature using Wien's Displacement Law.