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Answer:</h2><h2><u>QUESTION①)</u></h2>
✔First you have to calculate the light's speed in the glass,
<em>You know that in the air and in the void (where the refraction index n is zero) the light's speed C corresponds to 3,0 x 10^8 m/s</em>
So We have :
<em>V = C/n </em>
- V = 3,0 x 10^8/1,56
- V ≈ 1,92 x 10^8 m/s
✔ Now, you know the light's speed in glass, and you know that : the wavelength λ is the quotient of light's speed V on its frequency ν, so :
<em>λ = V/ ν </em>
- λ = 1,82 x 10^8/5,70 x 10^14
- λ ≈ 3.40 x 10^-7 m
- λ ≈ 340 nm
Answer:
r = 2.63 m
Explanation:
To find the distance at which the sound level is 120dB, you first calculate the intensity of the sound. You use the following formula:
(1)
β: sound level = 120dB
I: intensity of the sound
Io: threshold of hearing = 10⁻12W/m^2
You solve the equation (1) for I and replace the values of all parameters:
Next, you use the following formula for the power of the sound with intensity I, and you solve for r:
r: distance at which the sound level is 120dB
P: power of the sound = 87W
I: intensity of the sound = 1W/m^2
You replace the values of I and P for calculating r:
The distance is at 2.63m from the source of the soundr = 2.63m
Focuses light on the retina