I think the complete question is:
An old movie poster used a quote "In space, no one can hear you scream!" Which of these best explains the quote?
A) The quote is incorrect, you can hear sound in outer space.
B) Sound cannot be polarized. So, you cannot hear sound in space.
C) Sound is an electromagnetic wave and needs no medium to travel through.
D) Sound needs a medium for the wave to vibrate and there is nothing in space to vibrate.
Answer:
D) Sound needs a medium for the wave to vibrate and there is nothing in space to vibrate.
Explanation:
There are two types of waves:
- Mechanical Waves : These waves requires are medium to travel from one point of space to another point of space. Sound wave is one such example. Since they depend upon medium so speed of travelling also depend upon medium.
- Electromagnetic Waves : These type of waves do not require a medium to travel. If medium exists then it will cause some hindrance in there path but still they will travel. For example: Light waves, X-Rays, Microwaves, Infrared waves, Ultraviolet waves etc.
In space no particle exists so no mechanical waves, such as sound, can travel through it but any electromagnetic wave can travel, such as light. That is why when astronauts are in space walk or when they are in outer space then they do not talk rather they use sign language to communicate
