Use Gauss’ law to find the E-field outside of a long straight wire.
Question
Use Gauss’ law to find the E-field outside of a long straight wire.
Solution
Sure, here's how you can use Gauss' law to find the electric field outside of a long straight wire:
-
First, let's assume that the wire is infinitely long and has a uniform linear charge density λ (lambda).
-
Gauss' law states that the electric flux through a closed surface is equal to the charge enclosed by the surface divided by the permittivity of free space (ε0). Mathematically, it is represented as ∮E.dA = Q/ε0.
-
To apply Gauss' law, we need to choose a Gaussian surface. In this case, we choose a cylindrical Gaussian surface with the wire as the axis. The cylinder has a length L and radius r.
-
The electric field E due to the wire is directed radially outward from the wire. Therefore, the electric flux through the curved surface of the cylinder is E(2πrL), because E and dA are parallel on this surface.
-
The electric flux through the two end faces of the cylinder is zero, because E and dA are perpendicular on these surfaces.
-
The total charge enclosed by the Gaussian surface is λL, where λ is the linear charge density.
-
According to Gauss' law, the electric flux through the Gaussian surface is equal to the enclosed charge divided by the permittivity of free space. Therefore, we have E(2πrL) = λL/ε0.
-
Solving this equation for E, we get E = λ/(2πε0r).
So, the electric field outside a long straight wire of uniform linear charge density is directed radially outward from the wire and its magnitude decreases with the distance r from the wire as λ/(2πε0r).
Similar Questions
with the help of biot savarts law derive expression for magnetic field due to straight wire of length infinite carrying charge i
A long straight wire of circular cross section of radius a carries asteady current I. The current is uniformly distributed across itscross section. The ratio of the magnitudes of magnetic field at apoint distant a/2 above the surface of wire to that at a point distanta/2 below its surface is(i) 4 :1(ii) 1:1(iii) 4: 3(iv) 3 :4
A wire is 12.00 m long and has a diameter of 1.50 mm. The elastic modulus of the wire is 7.00 × 1010 N/m2. If a force of 500 N is applied to end of the wire, then the increase in length of the wire is
A copper wire has a resistivity of 1.723 x 10-8 Ω-m and a cross-sectional area of 9.5 mm2. Calculate the length of the wire in m when its resistance is 3.2 Ω.
A cylindrical wire of radius 0.5 mm and conductivity 5 × 107 S/m is subjected to an electric field of 10 mV/m. The expected value of current in the wire will be x3π mA. The value of x is ____.
Upgrade your grade with Knowee
Get personalized homework help. Review tough concepts in more detail, or go deeper into your topic by exploring other relevant questions.