One is the best choice for an answer.
Answer:
No Refraction takes places
Explanation:
When light travels from one medium to another at an angle of incidence 0 degree then no refraction takes place .
It is because according to Refraction law
sini =
sinr
where
are the refractive index of medium of incidence and medium of refraction .
When i = 0 , left side of the equation becomes 0 and thus r (angle of refraction) must be zero. So No refraction takes place
Answers:
a) 10 m
b) time=1.6 s, frquency=0.625 Hz
c) 6.25 m/s
Explanation:
a) If there is a crest at each dock and another three crests between the two docks, and the wavelength
is the distance between to crests; this means we have
in
:

Clearing
:


b) This part can be solved by a Rule of Three:
If 10 waves ---- 16 s
1 wave ----- 
Then:

This is the period of the wave
On the other hand, the frequency
of the wave has an inverse relation with its period
:


This is the frequency of the wave
c) The speed
of a wave is given by the following equation:


Finally:

He should a step-up transformer with k=220/120=1.83 so output coil must have 240*1.83=440 turns
There are four characteristics of a state. population,government,sovereignty,and territory.