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Explain how the displacement current maintains the continuity of current in a circuit containing a capacitor.
The current into the capacitor to change the electric field between the plates is equal to the displacement current between the plates.
Describe the field lines of the induced magnetic field along the edge of the imaginary horizontal cylinder shown below if the cylinder is in a spatially uniform electric field that is horizontal, pointing to the right, and increasing in magnitude.
Why is it much easier to demonstrate in a student lab that a changing magnetic field induces an electric field than it is to demonstrate that a changing electric field produces a magnetic field?
The first demonstration requires simply observing the current produced in a wire that experiences a changing magnetic field. The second demonstration requires moving electric charge from one location to another, and therefore involves electric currents that generate a changing electric field. The magnetic fields from these currents are not easily separated from the magnetic field that the displacement current produces.
Show that the magnetic field at a distance
r from the axis of two circular parallel plates, produced by placing charge
Q (
t ) on the plates is
.
Express the displacement current in a capacitor in terms of the capacitance and the rate of change of the voltage across the capacitor.
A potential difference
is maintained across a parallel-plate capacitor with capacitance
C consisting of two circular parallel plates. A thin wire with resistance
R connects the centers of the two plates, allowing charge to leak between plates while they are charging.
(a) Obtain expressions for the leakage current
in the thin wire. Use these results to obtain an expression for the current
in the wires connected to the capacitor.
(b) Find the displacement current in the space between the plates from the changing electric field between the plates.
(c) Compare
with the sum of the displacement current
and resistor current
between the plates, and explain why the relationship you observe would be expected.
a.
; b.
;
c.
; which is the sum of
and
consistent with how the displacement current maintaining the continuity of current.
Suppose the parallel-plate capacitor shown below is accumulating charge at a rate of 0.010 C/s. What is the induced magnetic field at a distance of 10 cm from the capacitator?
The potential difference V ( t ) between parallel plates shown above is instantaneously increasing at a rate of What is the displacement current between the plates if the separation of the plates is 1.00 cm and they have an area of ?
A parallel-plate capacitor has a plate area of and a separation of 0.0100 m. What must be must be the angular frequency for a voltage with to produce a maximum displacement induced current of 1.00 A between the plates?
The voltage across a parallel-plate capacitor with area and separation varies sinusoidally as , where t is in seconds. Find the displacement current between the plates.
The voltage across a parallel-plate capacitor with area A and separation d varies with time t as , where a is a constant. Find the displacement current between the plates.
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