Question

A thunder is heard 4 seconds after the lighting. At what distance, the lightning occured?

• A. 1480 m
• B. 1380 m
• C. 2380 m
• D. 1000 m

Answer 1

The correct option is B 1380 m

Answer is B.
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 sound is 340 m/s.Thus, the entire time of 4 seconds (as mentioned in the question) between seeing the light and hearing the thunderstorm is taken by the sound to travel to the observer. Hence, the distance traveled by the thunder is given as follows.s=vt; where,s is the distance traveled, v is the velocity of sound and t is the time taken. That is, 340 * 4 s = 1360 m.
Hence, distance the lightning occured is 1360 m. This is close to 1380 m mentioned in the options.