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Assertion : All electromagnetic waves ...

Assertion : All electromagnetic waves travel with same speed in vacuum .
Reason : speed of electromagnetic wave in a medium is given by speed of light in vacuum divided by refractive index of the material .

A

If both assertion and reason are correct and reason is a correct explanation of the assertion

B

IF both assertion and reason are correct but reson is not the correct explantion of assertion

C

If assertion is correct but reason is incorrect

D

IF assertion is incorrect but reason is correct .

Text Solution

AI Generated Solution

The correct Answer is:
To solve the question, we need to analyze both the assertion and the reason provided. ### Step 1: Analyze the Assertion The assertion states that "All electromagnetic waves travel with the same speed in vacuum." - This statement is true. In a vacuum, all electromagnetic waves, regardless of their frequency or wavelength, travel at the same speed, which is approximately \(3 \times 10^8\) meters per second (the speed of light). This is a fundamental property of electromagnetic waves. ### Step 2: Analyze the Reason The reason states that "The speed of electromagnetic wave in a medium is given by the speed of light in vacuum divided by the refractive index of the material." - This statement is also true. The speed of light in a medium can indeed be calculated using the formula: \[ v = \frac{c}{n} \] where \(v\) is the speed of light in the medium, \(c\) is the speed of light in vacuum, and \(n\) is the refractive index of the medium. This formula shows how the speed of light changes when it enters different materials. ### Step 3: Determine the Relationship between Assertion and Reason Now we need to determine if the reason provided correctly explains the assertion. - While both statements are true, the reason does not explain why all electromagnetic waves travel at the same speed in vacuum. The assertion is a general statement about the behavior of electromagnetic waves in vacuum, while the reason pertains to their behavior in a medium. Thus, the reason does not serve as an explanation for the assertion. ### Conclusion - Therefore, we conclude that: - The assertion is true. - The reason is true. - However, the reason is not the correct explanation for the assertion. ### Final Answer Both the assertion and reason are true, but the reason is not the correct explanation of the assertion. ---
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Knowledge Check

  • The speed of electromagnetic wave in vacuum

    A
    Increases as we move from `gamma`-rays to radio waves
    B
    Decreases as move from `gamma`-rays to radio waves
    C
    Is same for all of them
    D
    None of these

  • The speed of electromagnetic waves in air is

    A
    `3 xx 10^(5)` km/s
    B
    `3 xx 10^(6)` km/s
    C
    `3 xx 10^(7)` km/s
    D
    `3 xx 10^(8)` km/s

  • Speed of electromagnetic waves is given

    A
    `c = (1)/sqrt(mu_(0)epsi_(0))`
    B
    `c = sqrt(mu_(0)epsi_(0))`
    C
    `c = (1)/(mu_(0)epsi_(0))`
    D
    `c = mu_(0)epsi_(0)`

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