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Question

Wavelength and frequency of a radio wave are 12 m and 25 ×  10Hz respectively. Calculate its velocity. 

The correct answer is 3 ×  108 m/s

Calculating Radio Wave Velocity

The velocity of a wave, including a radio wave which is an electromagnetic wave, is related to its frequency and wavelength by a fundamental formula.

The relationship is given by:

$\text{Velocity} = \text{Frequency} \times \text{Wavelength}$

In terms of symbols:

$v = \nu \lambda$

Where:

  • $v$ is the velocity of the wave.
  • $\nu$ (nu) is the frequency of the wave.
  • $\lambda$ (lambda) is the wavelength of the wave.

In this problem, we are given the following values for the radio wave:

  • Wavelength ($\lambda$) = 12 m
  • Frequency ($\nu$) = $25 \times 10^6$ Hz

Now, we can substitute these values into the formula to calculate the velocity of the radio wave.

Step-by-Step Calculation of Radio Wave Velocity

  1. Identify the given values:
    $\lambda = 12 \text{ m}$
    $\nu = 25 \times 10^6 \text{ Hz}$
  2. Write down the formula relating velocity, frequency, and wavelength:
    $v = \nu \lambda$
  3. Substitute the given values into the formula:
    $v = (25 \times 10^6 \text{ Hz}) \times (12 \text{ m})$
  4. Perform the multiplication:
    $v = (25 \times 12) \times 10^6 \text{ m/s}$
    $v = 300 \times 10^6 \text{ m/s}$
  5. Express the result in standard scientific notation (optional but often required):
    $300 = 3 \times 10^2$
    So, $v = (3 \times 10^2) \times 10^6 \text{ m/s}$
    $v = 3 \times 10^{2+6} \text{ m/s}$
    $v = 3 \times 10^8 \text{ m/s}$

The calculated velocity of the radio wave is $3 \times 10^8$ m/s. This value is approximately the speed of light in a vacuum, which is expected for electromagnetic waves like radio waves.

Comparing this result with the given options, we find that it matches option 2.

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Important Questions from Waves

  1. Visible light's wavelength range _________.

  2. If the frequency of a sound wave is 50 Hz, then what is its time period?

  3. Hertz is the SI unit of ________.

  4. A running race is organized between ultrasonics, audible and infrasonic waves in a medium, then the winner is:

  5. When a light wave travels from air to water, then which property remain unchanged ?

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