Answer:
Time moves slower and length decreases.
Explanation:
For this case you must first know the definition of density.
D = m / v
where,
m: mass
v: volume.
You can then write the following hypothesis:
IF you know two physical characteristics of an object then you can determine the density. First weigh the object, THEN measure its volume BECAUSE the density is the quotient between the mass and the volume of an object.
To solve this problem it is necessary to take into account the concepts of Intensity as a function of Power and the definition of magnetic field.
The intensity depending on the power is defined as
![I = \frac{P}{4\pi r^2},](https://tex.z-dn.net/?f=I%20%3D%20%5Cfrac%7BP%7D%7B4%5Cpi%20r%5E2%7D%2C)
Where
P = Power
r = Radius
Replacing the values that we have,
![I = \frac{60}{(4*\pi (0.7)^2)}](https://tex.z-dn.net/?f=I%20%3D%20%5Cfrac%7B60%7D%7B%284%2A%5Cpi%20%280.7%29%5E2%29%7D)
![I = 9.75 Watt/m^2](https://tex.z-dn.net/?f=I%20%3D%209.75%20Watt%2Fm%5E2)
The definition of intensity tells us that,
![I = \frac{1}{2}\frac{B_o^2 c}{\mu}](https://tex.z-dn.net/?f=I%20%3D%20%5Cfrac%7B1%7D%7B2%7D%5Cfrac%7BB_o%5E2%20c%7D%7B%5Cmu%7D)
Where,
Magnetic field
Permeability constant
c = Speed velocity
Then replacing with our values we have,
![9.75 = \frac{Bo^2 (3*10^8)}{(4\pi*10^{-7})}](https://tex.z-dn.net/?f=9.75%20%3D%20%5Cfrac%7BBo%5E2%20%283%2A10%5E8%29%7D%7B%284%5Cpi%2A10%5E%7B-7%7D%29%7D)
Re-arrange to find the magnetic Field B_0
![B_o = 2.86*10^{-7} T](https://tex.z-dn.net/?f=B_o%20%3D%202.86%2A10%5E%7B-7%7D%20T)
Therefore the amplitude of the magnetic field of this light is