Assertion : The velocity of electromagnetic waves depends on electric and magnetic properties of the medium
Reason : Velocity of electromagnetic waves in free space is constant.

Options

A. If both assertion and reason are true and reason is the correct explanation of assertion
B. If both assertion and reason are true but reason is not the correct explanation of assertion
C. If assertion is true but reason is false
D. If both assertion and reason are false

Explanation

To analyze the given assertion and reason, we will break down the statements step by step.

### Step 1: Understanding the Assertion
The assertion states that "The velocity of electromagnetic waves depends on electric and magnetic properties of the medium."

- **Explanation**: The velocity of electromagnetic waves in a medium is influenced by the medium's electric permittivity (ε) and magnetic permeability (μ). The formula for the velocity (v) of electromagnetic waves in a medium is given by:

\[ v = \frac{1}{\sqrt{\mu \epsilon}} \]

Here, μ represents the permeability of the medium, and ε represents the permittivity of the medium. Hence, the assertion is true because the speed of electromagnetic waves is indeed dependent on these properties.

### Step 2: Understanding the Reason
The reason states that "Velocity of electromagnetic waves in free space is constant."

- **Explanation**: In free space (or vacuum), the speed of electromagnetic waves is constant and is denoted by 'c', which is approximately \(3 \times 10^8 \, \text{m/s}\). This is a fundamental constant of nature. Therefore, this statement is also true.

### Step 3: Analyzing the Relationship Between Assertion and Reason
While both the assertion and reason are true, we need to determine if the reason correctly explains the assertion.

- **Explanation**: The assertion discusses how the velocity of electromagnetic waves is influenced by the properties of the medium, while the reason simply states that in free space, the velocity is constant. The reason does not provide an explanation for why the velocity depends on electric and magnetic properties in other media. Therefore, the reason does not adequately explain the assertion.

### Conclusion
Both the assertion and the reason are true, but the reason is not the correct explanation of the assertion.

Thus, the correct answer is: **Both assertion and reason are true, but reason is not the correct explanation of assertion.**

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