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**a long straight wire has fixed -ve charge density of 39nC/m. the wire is enclosed by thin wall non conducting coaxial cylinder of radius 1.7m. the shall has positive charge density and its Field is such as that it will cancel the field due to wire. what will be the surface charge density of cylinder.**

**2. Relevant equations**

E=lamda/2pi€r

gausses law

**3. The attempt at a solution**

first i have found the the electric field of wire enclosed in cylinderusing equation E=lamda/2pi€r. then as given total electric field must be zero so E for cylinder must be same in magnitude as of wire but opposite sign. but i have no idea i am attempt towards solution is right or wrong any help??