Answer: wavelength !!
hope this helped :)
Answer:
0.25 m
Explanation:
Electromagnetic waves consist of oscillations of the electric and the magnetic field, oscillating in a plane perpendicular to the direction of motion the wave.
All electromagnetic waves travel in a vacuum always at the same speed, the speed of light, whose value is:
Microwave is an example of electromagnetic waves.
The relationship between wavelength and frequency for an electromagnetic wave is:

where
is the wavelength
is the speed of light
f is the frequency
For the microwave in this problem,

So its wavelength is

Acceleration of an object is depended upon the net force acting open the object and the mass of the object
Answer:
emf will also be 10 times less as compared to when it has fallen 
Explanation:
We know, from faraday's law-

and 
So, as the height increases the velocity with which it will cross the ring will also increase. 
Given


Now, from 

From equation a and b we see that velocity when dropped from
is 10 times greater when height is 40
so, emf will also be 10 times less as compared to when it has fallen 
I believe this is known as wave period.
hope this helps!