Answer:
18.89cm
Explanation:
As we know that the person is standing 5m in front of the camera

The focal length of the lens =50cm
f=50 cm
By Lens formula we have:

By the formula of magnification

The height of the image formed is 18.89cm.
Answer:
The new resistance comes out to be = 4 times of original resistance .
Heat, like sound, is kinetic energy. Molecules at higher temperatures heave more energy, thus they can vibrate faster. Since the molecules vibrate faster, sound waves can travel more quickly.
So the answer is A.