Tag: comparison of speed of sound with speed of light

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Multiple choice physics propagation of sound waves longitudinal vs transverse wave sound and light comparison of speed of sound with speed of light

Flash and thunder are produced simultaneously. But thunder is heard a few seconds after the flash is seen. This is because:

  1. speed ofsound is greater than speed oflight

  2. speed of sound is equal to the speed of light

  3. speed of light is much greater than the speed of sound

  4. none of these
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

It is because light travels faster  ($3\times10^{8}m/s$) than sound ($332m/s$) , so we hear thunder after a few second of the flash .

Multiple choice physics propagation of sound waves longitudinal vs transverse wave sound and light comparison of speed of sound with speed of light

Correct comparison between light waves and sound waves is:

  1. Both are mechanical waves

  2. Both need a material medium for propagation

  3. Both can travel through vacuum

  4. None
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Sound waves are mechanical waves, light waves are electromagnetic waves. Light can travel through vacuum, sound cannot.

Multiple choice physics propagation of sound waves longitudinal vs transverse wave sound and light comparison of speed of sound with speed of light

The distance between tow adjacent particles which are in the same phase in a progressive wave is 20 cm. determine the velocity of the wave if its frequency is 10 Hz.

  1. $2 {ms}^{-1}$

  2. $40 {ms}^{-1}$

  3. $8 {ms}^{-1}$

  4. $80 {ms}^{-1}$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The distance between two adjacent particles in the same phase is the wavelength (lambda). Given lambda = 20 cm = 0.2 m and frequency f = 10 Hz, the velocity v = f * lambda = 10 * 0.2 = 2 m/s.

Multiple choice physics propagation of sound waves longitudinal vs transverse wave sound and light comparison of speed of sound with speed of light

Light and Sound waves

  1. both are mechanical waves

  2. both need material media for propagation

  3. both can travel through vacuum

  4. are two different types of waves
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Sound waves are mechanical waves which are longitudinal in nature and require material media to pass through.

Light waves are electromagnetic waves which are transverse in nature and do not require any material medium to pass through.

Multiple choice physics propagation of sound waves longitudinal vs transverse wave sound and light comparison of speed of sound with speed of light

The thunder of a cloud is heard later compared to flash of lightning because :

  1. speed of sound is greater than speed of light

  2. <span>speed of light is greater than speed of sound</span>

  3. <span>speed of sound is the same as speed of light</span>

  4. sound is obscured by the rain
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The light travels much faster than the sound. The thunder travels at the speed of sound while the light from the flash travels at the speed of the light. The speed of light is about 340 m/s through air, while the speed of light is about 300 million m/s.So the thunder is heard after the flash of lightening.

Multiple choice physics propagation of sound waves longitudinal vs transverse wave sound and light comparison of speed of sound with speed of light

You see lightning before you hear the thunder because

  1. Lightning is much brighter than thunder.

  2. Thunder is heavier than lightning.

  3. Light can travel through air but sound cannot.

  4. Sound travels slower than light.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Answer is D.

Lightning and thunder are produced simultaneously, but the thunder is heard a few seconds after the lightning is seen. This is because the speed of light in air is more than the speed of sound in air.The speed of light is given as $3\times { 10 }^{ 8 }m/s$. The speed of sound is 340 m/s.
Hence, the flash of lightning is seen before the thunder is heard as the speed of sound is less than speed of light.