The surface area
of the curved part is  2prl, where l is the length
of the cylinder FIGURE 1 26 (a) Electric field due to an
infinitely long thin straight wire is radial,
(b) The Gaussian surface for a long thin
wire of uniform linear charge density Rationalised 2023-24
34
Physics
Flux through the Gaussian surface
=
flux through the curved cylindrical part of the surface
=
E × 2prl
The surface includes charge equal to l l