In: Physics
A positive point charge Q1 = 1.8 ?
10-5 C is fixed at the origin of coordinates, and a
negative charge Q2 = -3.6 ? 10-6 C
is fixed to the x axis at x = +2.0 m. Find the
location of the place(s) along the x axis where the
electric field due to these two charges is zero. (Enter the
locations in order from -x to +x. If there is
only 1 location, enter 0 as the second answer.)
x = ______ m
x = ______ m
he positive charge at the origin is so much greater than the
negative, then the field lines going from it are going to be pretty
great, despite the farther distance from it. So you can conclude at
some point out there beyond x =2, that the Electric field from the
positive charge is going to cancel the electric field going to the
negative. And I'll tell you that it should be pretty far out there
probably because that +charge is a 1000x more greater than the
negative charge. But remember too that distance is inversely
proportional, so I guess it won't be "that" far out. But far
nonetheless.
So call the electric field due to the + charge E1 and the field due
to - charge E2. x, where the Enet = 0, will be the distance from
the + charge at the origin.
Enet = 0 = E1 - E2
E1 = E2
kQ1 / x^2 = kQ2 / (x +2)^2
And then of course k = 9x10^9, Q1 = 1.8x10^-5 and Q2 =
-3.5x10^-6.After k gets cancelled
Q1 / x^2=Q2 / (x +2)^2
.8x10^-5/x*2=-3.5x10^-6/(2+2)^2
220=16 x^2
x=3.75 m