Which of the following statements are correct?

Options

A. Rough surfaces are better reflector than smooth surfaces
B. Highly polished mirror like surfaces are very. Good radiators
C. Black surfaces are better absorbers than white ones
D. Black surfaces are better radiators than white ones

Answer

To determine which statements are correct, let's analyze each option step by step.

### Step 1: Analyze the first statement
**Statement 1:** Rough surfaces are better reflectors than smooth surfaces.

- **Explanation:** When light or energy strikes a smooth surface, such as a mirror, it reflects in a uniform direction, making it a good reflector. In contrast, rough surfaces scatter the incident energy in various directions, leading to less effective reflection and more absorption of energy. Therefore, rough surfaces are not better reflectors than smooth surfaces.

**Conclusion:** This statement is **incorrect**.

### Step 2: Analyze the second statement
**Statement 2:** Highly polished mirror surfaces are very good radiators.

- **Explanation:** Highly polished surfaces, like mirrors, are excellent reflectors of energy. They reflect most of the incident energy rather than absorbing it. According to the principles of thermodynamics, a surface that does not absorb energy well cannot radiate energy effectively. Therefore, polished mirror surfaces are not good radiators.

**Conclusion:** This statement is **incorrect**.

### Step 3: Analyze the third statement
**Statement 3:** Black surfaces are better absorbers than white ones.

- **Explanation:** Black surfaces are known to absorb a significant amount of incident energy, with an absorptivity of 1 (ideal black body). In contrast, white surfaces reflect most of the incident energy and absorb very little. Thus, black surfaces are indeed better absorbers compared to white surfaces.

**Conclusion:** This statement is **correct**.

### Step 4: Analyze the fourth statement
**Statement 4:** Black surfaces are better radiators than white ones.

- **Explanation:** According to the principle of thermal radiation, a good absorber is also a good radiator. Since black surfaces absorb more energy, they also radiate energy more effectively than white surfaces, which reflect most of the energy. Therefore, black surfaces are indeed better radiators than white surfaces.

**Conclusion:** This statement is **correct**.

### Final Summary of Statements
1. Incorrect
2. Incorrect
3. Correct
4. Correct