Answer:

Explanation:
Torque is defined as the cross product between the position vector ( the lever arm vector connecting the origin to the point of force application) and the force vector.

Due to the definition of cross product, the magnitude of the torque is given by:

Where
is the angle between the force and lever arm vectors. So, the length of the lever arm (r) is minimun when
is equal to one, solving for r:

efficiency= [useful energy transferred ÷ total energy supply]×100%
So, [5500÷10000]×100%=0.55×100
=55%
Complete Question:
A beam of white light is incident on the surface of a diamond at an angle
, since the index of refraction depends on the light's wavelength, the different colors that comprise white light will spread out as they pass through the diamond. For example, the indices of refraction in diamond are
for red light and
for blue light. Thus, blue light and red light are refracted at different angles inside the diamond. The surrounding air has
.
Now consider θc, the angle at which the blue refracted ray hits the bottom surface of the diamond. If θc is larger than the critical angle θcrit, the light will not be refracted out into the air, but instead it will be totally internally reflected back into the diamond. Find θcrit. Express your answer in degrees to four significant figures.
Answer:

Explanation:
Only the blue refracted ray is related to the critical angle in this question


The relationship between the critical angle(
),
and
can be given as 

Answer:
Part a)
f = 1911.5 Hz
Part b)

Explanation:
Here the source and observer both are moving towards each other
so we know that the apparent frequency is given as

here we know that



now we will have


Part b)
Apparent wavelength is given by the formula

here we will have

