Explain why the flash of lightning reaches us first and the sound of thunder is heard a little later.

Hint: To answer this type of question we must know about the properties of sound as well as light. If we knew this this would be very easy to answer. Here in this question, we will understand the properties and then according to the question we will decide and conclude the answer in this way will get our required solution.

Complete answer:
As we know that the speed of the light is something \[3 \times {10^8}\,m{\text{ }}{s^{ - 1}}\] Where as the speed of sound is only $343\,m{\text{ }}{{\text{s}}^{ - 1}}$. As above we can see that there is a very big difference in the speed of light and sound resulting, we can say that we will hear the sound of the lightning later and flash of the flash of lightning before.

Note: This happens in our surroundings and the above speed of sound is at ${20^ \circ }C$ . Whereas if we examine the same in vacuum, we will come to know that there is no sound of the lightning and this is because sound needs a medium to travel and in vacuum there is no medium so we cannot hear the sound of lightning and only can see the flash.