(a) Two identical open boxes originally contain the same volume of water. One is kept at 15°C and the other at 85°C for the same
length of time.
Fig. 4.1 shows the final water levels.
With reference to the energies of the water molecules, explain why the levels are different.
Fig. 4.1 shows the final water levels.
With reference to the energies of the water molecules, explain why the levels are different.
1 answer:
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Answer:
B = 38.2μT
Explanation:
By the Ampere's law you have that the magnetic field generated by a current, in a wire, is given by:
(1)
μo: magnetic permeability of vacuum = 4π*10^-7 T/A
r: distance from the center of the cylinder, in which B is calculated
Ir: current for the distance r
In this case, you first calculate the current Ir, by using the following relation:
J: current density
Ar: cross sectional area for r in the hollow cylinder
Ar is given by
The current density is given by the total area and the total current:
R2: outer radius = 26mm = 26*10^-3 m
R1: inner radius = 5 mm = 5*10^-3 m
IT: total current = 4 A
Then, the current in the wire for a distance r is:
(2)
You replace the last result of equation (2) into the equation (1):
Finally. you replace the values of all parameters:
hence, the magnitude of the magnetic field at a point 12 mm from the center of the hollow cylinder, is 38.2μT