Choose the correct expression of power and Intensity of em wave?

Options

A. Power = Intensity + c
B. Power = Intensity + vc
C. Power = Intensity `xx` Area
D. None of the above

Explanation

To solve the question regarding the correct expression of power and intensity of electromagnetic waves, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Intensity**:
- Intensity (I) of an electromagnetic wave is defined as the energy per unit area per unit time. Mathematically, it can be expressed as:
\[ I = \frac{E}{A \cdot t} \]
where \(E\) is the energy, \(A\) is the area, and \(t\) is the time.

2. **Understanding Power**:
- Power (P) is defined as the rate at which energy is transferred or converted. It can be expressed as:
\[ P = \frac{E}{t} \]
where \(E\) is the energy and \(t\) is the time.

3. **Relating Power and Intensity**:
- Since intensity is energy per unit area per unit time, we can rearrange the equation for intensity to express power in terms of intensity and area:
\[ I = \frac{P}{A} \]
- Rearranging this gives us:
\[ P = I \cdot A \]

4. **Identifying the Correct Option**:
- From the derived relationship, we see that the correct expression for power in terms of intensity and area is:
\[ P = I \cdot A \]
- Therefore, the correct option from the given choices is option three: "power equals to intensity into area".

### Final Answer:
The correct expression of power in terms of intensity of an electromagnetic wave is:
\[ P = I \cdot A \]