The electric field lines from an isolated positively charged conducting sphere are

CONCEPT:

• Since for a conducting solid sphere, the charge is only present at the surface, so the electric field intensity inside the conducting solid sphere is zero.
• This can be proven using Gauss's law.

Gauss's law:

• According to Gauss law, the total electric flux linked with a closed Gaussian surface called Gaussian surface is \(\frac{1}{ϵ_o}\) times the charge enclosed by the closed surface.

EXPLANATION:

• If we draw a Gaussian sphere inside the conducting sphere for r < R then there is no charge enclosed inside the Gaussian surface.

⇒ ϕ  = 0 

• No electric flux is involved with the  Gaussian sphere so there will be no electric field lines inside the Gaussian sphere but for the representation purpose, these lines will be perpendicular to the spherical surface and radially outside the surface as the conducting sphere is positively charged (Since the conducting sphere can be treated as an equipotential surface)
• Hence, option 4 is correct.​