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This is a conceptually tricky question that tests understanding of electromagnetic spectrum. Option A is wrong as a standalone answer. Radio waves are electromagnetic waves and in vacuum they travel at the same speed as light (3×10⁸ m/s). They are not faster than light. Option B is wrong as a standalone answer. X-rays are also electromagnetic waves and travel at exactly the same speed as light in vacuum (3×10⁸ m/s). Higher frequency/energy does not mean higher speed for EM waves in vacuum. Option C is wrong as a standalone answer. Visible light is also an electromagnetic wave traveling at 3×10⁸ m/s in vacuum — same as all other EM waves. Option D is CORRECT. The image states: कास्मिक किरण, प्रकाश, इलेक्ट्रान एवं परायोनिक तरंग में से किसका वेग अधिकतम होता है — प्रकाश का. ALL electromagnetic waves (radio waves microwaves infrared visible light UV X-rays gamma rays) travel at exactly the same speed in vacuum: c = 3×10⁸ m/s. They differ in frequency and wavelength but NOT in speed in vacuum. Cosmic rays are charged particles (protons electrons) and travel SLOWER than light. Therefore among the EM waves listed all have equal maximum speed of 3×10⁸ m/s.
FAQ
Common questions and clear answers for this topic.
Optics is the branch of physics that studies the behavior of light, including its reflection, refraction, and interaction with lenses and mirrors.
Reflection is the bouncing back of light when it strikes a surface, while refraction is the bending of light as it passes from one medium to another with a different optical density.
A lens is a transparent optical device with curved surfaces that refracts light to converge or diverge rays, commonly classified as convex (converging) or concave (diverging).
The speed of light in a vacuum is approximately 3 x 10^8 meters per second, denoted by the symbol c.
Total internal reflection occurs when light traveling from a denser medium to a rarer medium strikes the boundary at an angle greater than the critical angle, causing it to be completely reflected back into the denser medium.
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