Where do the electrons that form the auroras enter the magnetosphere? a. Through holes c. At the equator b. Between the magnetic
2 answers:
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a) E = 0
b)
Explanation:
a)
We can solve this problem using Gauss theorem: the electric flux through a Gaussian surface of radius r must be equal to the charge contained by the sphere divided by the vacuum permittivity:
where
E is the electric field
q is the charge contained by the Gaussian surface
is the vacuum permittivity
Here we want to find the electric field at a distance of
r = 12 cm = 0.12 m
Here we are between the inner radius and the outer radius of the shell:
However, we notice that the shell is conducting: this means that the charge inside the conductor will distribute over its outer surface.
This means that a Gaussian surface of radius r = 12 cm, which is smaller than the outer radius of the shell, will contain zero net charge:
q = 0
Therefore, the magnitude of the electric field is also zero:
E = 0
b)
Here we want to find the magnitude of the electric field at a distance of
r = 20 cm = 0.20 m
from the centre of the shell.
Outside the outer surface of the shell, the electric field is equivalent to that produced by a single-point charge of same magnitude Q concentrated at the centre of the shell.
Therefore, it is given by:
where in this problem:
is the charge on the shell
is the distance from the centre of the shell
Substituting, we find:
Answer:
Part a)
here friction force will accelerate the box in forward direction
Part b)
a = 3.14 m/s/s
Explanation:
Part a)
When truck accelerates forward direction then the box placed on the truck will also move with the truck in same direction
Here if they both moves together with same acceleration then the force on the box is due to friction force between the box and the surface of the truck
So here friction force will accelerate the box in forward direction
Part b)
The maximum value of friction force on the box is known as limiting friction
it is given by the formula
so we have
now the acceleration is given as