Question:
The electromagnetic waves travel with
The electromagnetic waves travel with
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Remember that while the speed and wavelength of an EM wave change when it enters a different medium, its \textbf{frequency} always remains constant.
Updated On: Apr 20, 2026
- the same speed in all media
- the speed of sound in free space
- the speed of light \( c = 3 \times 10^{8} \) ms⁻¹ in solid medium
- the speed of light \( c = 3 \times 10^{8} \) ms⁻¹ in fluid medium
- the speed of light \( c = 3 \times 10^{8} \) ms⁻¹ in free space
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The Correct Option is
Solution and Explanation
Step 1: Understanding the Concept:
Electromagnetic (EM) waves are transverse waves consisting of oscillating electric and magnetic fields. In a vacuum or free space, all EM waves, regardless of their frequency or wavelength, travel at a constant universal speed denoted by \( c \).
Step 2: Detailed Explanation:
1. The speed of EM waves in a vacuum is defined by the constants of permittivity (\( \epsilon_0 \)) and permeability (\( \mu_0 \)) of free space: \( c = \frac{1}{\sqrt{\mu_0 \epsilon_0}} \).
2. This value is approximately \( 3 \times 10^{8} \) m/s.
3. In any other medium (solid or fluid), the speed decreases depending on the refractive index of that medium (\( v = c/n \)). Therefore, options (C) and (D) are incorrect because the speed in those media is less than \( c \).
Step 3: Final Answer:
EM waves travel with the speed of light \( c = 3 \times 10^{8} \) ms⁻¹ in free space.
Electromagnetic (EM) waves are transverse waves consisting of oscillating electric and magnetic fields. In a vacuum or free space, all EM waves, regardless of their frequency or wavelength, travel at a constant universal speed denoted by \( c \).
Step 2: Detailed Explanation:
1. The speed of EM waves in a vacuum is defined by the constants of permittivity (\( \epsilon_0 \)) and permeability (\( \mu_0 \)) of free space: \( c = \frac{1}{\sqrt{\mu_0 \epsilon_0}} \).
2. This value is approximately \( 3 \times 10^{8} \) m/s.
3. In any other medium (solid or fluid), the speed decreases depending on the refractive index of that medium (\( v = c/n \)). Therefore, options (C) and (D) are incorrect because the speed in those media is less than \( c \).
Step 3: Final Answer:
EM waves travel with the speed of light \( c = 3 \times 10^{8} \) ms⁻¹ in free space.
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