Electromagnetic waves do not require a medium to travel through. They can travel through empty space or matter.
They move in a waves motion
Given parameters:
Initial velocity of Coin = 0m/s
Time taken before coin hits ground = 5.7s
Unknown:
Final velocity of the coin = ?
Velocity is displacement with time. To solve this problem, we have to apply one of the equations of motion.
The fitting one of them here is shown below;
V = U + gt
where;
V is the final velocity
U is the initial velocity
g is the acceleration due to gravity
t is the time taken
Here we use positive value of acceleration due to gravity because the coin is falling with the effect of acceleration and not against it.
Now input the parameters and solve;
V = 0 + 9.81 x 5.7
V = 55.917m/s
Therefore, the final velocity is 55.917m/s.
Each
ion contains three extra protons. Hence, the extra charge on each
=
C
Total charge = 0.035 pC
Total charge (Q) =
C
Let the number of
ions be n.
According to question:



n = 72917
Hence, the total number of ions needed to be transferred is 72917
Answer
given,
wavelength (λ)= 500 n m
thickness of film= 10⁻⁴ cm
refractive index = μ = 1.375
distance traveled is double which is equal to 2 x 10⁻⁴ cm
a) Number of wave


N = 2.91
N = 3
b) phase difference is equal to
Reflection from the first surface has a 180° (½λ) phase change.
There is no phase change for the 2nd surface reflection and there is no phase difference for the 2nd wave having traveled an exact whole number of waves.
net phase difference = 
= 270°