Grace rides her bike at a constant speed of 6 miles per hour. How far can she travel in 2 1/2 hours?
1 answer:
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<h2>Answers:</h2>
The speed of a wave is given by:
(1)
Where is the frequency and
the wavelength.
In the case of light, its speed is:
(2)
On the other hand, the described situation is known as Refraction, a phenomenon in which the light changes its direction when passing through a medium with a refractive index different from the other medium.
In this context, the Refractive index is a number that describes how fast light propagates through a medium or material, and is defined as the relation between the speed of light in vacuum (
) and the speed of light
in the second medium:
(3)
In addition, as the light changes its direction, its wavelength changes as well:
(4)
Knowing this, let's begin with the answers:
<h2>a) Frequency</h2>From equation (2) we can find :
(5)
Knowing that :
(6) >>>Frequency of the helium-neon laser light
We already know the wavelength of the light in air and the index of refraction of the glass.
So, we only have to find the wavelength in glass from equation (4):
(7) >>>Wavelength of the helium-neon laser light in glass
From equation (3) we can find the speed of this light in glass:
(8) >>>Speed of the helium-neon laser light in glass
Answer:
The magnitude of the force the light beam exerts on the man is 5.9 x 10⁻⁵N
(b) the force the light beam exerts is much too small to be felt by the man.
Explanation:
Given;
cross-sectional area of the man, A = 0.500m²
intensity of light, I = 35.5kW/m²
If all the incident light were absorbed, the pressure of the incident light on the man can be calculated as follows;
P = I/c
where;
P is the pressure of the incident light
I is the intensity of the incident light
c is the speed of light
F = PA
where;
F is the force of the incident light on the man
P is the pressure of the incident light on the man
A is the cross-sectional area of the man
F = 1.18 x 10⁻⁴ x 0.5 = 5.9 x 10⁻⁵ N
The magnitude of the force the light beam exerts on the man is 5.9 x 10⁻⁵ N
Therefore, the force the light beam exerts is much too small to be felt by the man.