Sound intensity, I, from a spherical source is a function of the distance, r, from the source of the sound. It is represented by
1 answer:
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Answer:
292.3254055 W/m²
469.26267 V/m
Explanation:
P = Power of bulb = 90 W
d = Diameter of bulb = 7 cm
r = Radius =
= Permittivity of free space =
c = Speed of light =
The intensity is given by
5% of this energy goes to the visible light so the intensity is
The visible light intensity at the surface of the bulb is 292.3254055 W/m²
Energy density of the wave is
Energy density is also given by
The amplitude of the electric field at this surface is 469.26267 V/m
Amplitude of a magnetic field is given by
The amplitude of the magnetic field at this surface is
Answer:
The current in a resistor decreases by a factor of 4.
Explanation:
I =
Where (I) is the current, (E) is the voltage and (R) is the resistance.
Decreasing the voltage by 4 gives;
I = 0.25
Since you have multiplied by 0.25,
You have to multiply I by 0.25 so the current decreases by a factor of 4.