Four point charges have the same magnitude of 2.4×10^−12C and are fixed to the corners of a square that is 4.0 cm on a side. Thr
ee of the charges are positive and one is negative. Determine the magnitude of the net electric field that exists at the center of the square.
1 answer:
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(a) We can find the current flowing between the walls by using Ohm's law:
where
is the potential difference and 
is the resistance. Substituting these values, we get
(b) The total charge flowing between the walls is the product between the current and the time interval:
The problem says
, so the total charge is
The current consists of Na+ ions, each of them having a charge of
. To find the number of ions flowing, we can simply divide the total charge by the charge of a single ion:
where
(b) The total charge flowing between the walls is the product between the current and the time interval:
The problem says
The current consists of Na+ ions, each of them having a charge of
Answer:
a) fem = - 2.1514 10⁻⁴ V, b) I = - 64.0 10⁻³ A, c) P = 1.38 10⁻⁶ W
Explanation:
This exercise is about Faraday's law
fem =
where the magnetic flux is
Ф = B x A
the bold are vectors
A = π r²
we assume that the angle between the magnetic field and the normal to the area is zero
fem = - B π 2r dr/dt = - 2π B r v
linear and angular velocity are related
v = w r
w = 2π f
v = 2π f r
we substitute
fem = - 2π B r (2π f r)
fem = -4π² B f r²
For the magnetic field of Jupiter we use the equatorial field B = 428 10⁻⁶T
we reduce the magnitudes to the SI system
f = 2 rev / s (2π rad / 1 rev) = 4π Hz
we calculate
fem = - 4π² 428 10⁻⁶ 4π 0.10²
fem = - 16π³ 428 10⁻⁶ 0.010
fem = - 2.1514 10⁻⁴ V
for the current let's use Ohm's law
V = I R
I = V / R
I = -2.1514 10⁻⁴ / 0.00336
I = - 64.0 10⁻³ A
Electric power is
P = V I
P = 2.1514 10⁻⁴ 64.0 10⁻³
P = 1.38 10⁻⁶ W