To deduce coulomb’s law from Gaussis theorem: Consider that two point charge q1 and q2 are placed at point A and B at a distance r apart in vacuum. Let E is magnitude of electric field at the location of point charge q2 due to charge q2 Then force experienced by the point charge q2 due to electric field of charge q1.
F = q2E
To find E, draw a spherical surface of radius r with point as the centre. According to Gauss theorem, the total electric flux.
It is the mathematical from of Coulomb’s law in electrostatics.
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west of the geographic north. The north tip of the magnetic needle of a dip circle placed in the plane of magnetic meridian points above the horizontal. The horizontal component of the earth’s field is measured to be 
Specify the direction and magnitude of the earth’s field at the location.At a certain location in Africa, a compass points 
and 
carrying currents of 
and 
in the same direction are separated by a distance of 
. Estimate the force on a 
section of wire A.
wire carrying a current of 
is placed inside a solenoid perpendicular to its axis. The magnetic field inside the solenoid is given to be 
. What is the magnetic force on the wire?
and making an angle of 
with the direction of a uniform magnetic field of 
. What is the magnitude of the field 
at a point 
from the wire?
-turns carrying current 
.
is at distance 
from the wire. Find the force acting on the electron if its velocity is directed towards the wire.