Exams › JEE Main › Physics

Three concentric conducting spherical shells A, B and C (A innermost, C outermost) are given charges Q, 2Q and -Q respectively. Find the ratio of the charge on the inner surface of shell C to the charge on its outer surface.

1. 3/4
2. -3/4
3. 3/2
4. -3/2

Correct answer: -3/2

Solution

Total charge enclosed by C's inner surface (A + B) is Q + 2Q = 3Q, so C's inner surface must be -3Q. C carries -Q total, so its outer surface = -Q - (-3Q) = +2Q. The ratio (inner)/(outer) = (-3Q)/(+2Q) = -3/2.

Related JEE Main Physics questions

• If an electric field vector E exists in a material whose dielectric constant is K, and ε0 denotes the permittivity of free space, which expression gives the electric displacement vector?
• If a unit positive charge is taken from point A to point B along the same equipotential surface, then what can be said about the potential difference V_A - V_B?
• Two thin metallic spherical shells are placed concentrically with radii R1 and R2, where R1 > R2. If the shells carry charges Q1 and Q2 respectively, what is the electric potential at a point located at distance r such that R2 < r < R1? (Take k = 1/(4πϵ0))
• An alpha particle is made to move through a potential difference of 10⁶ V. What kinetic energy does it gain?
• A parallel-plate capacitor has its entire gap filled with a dielectric whose dielectric constant changes with position x according to K(x) = K0 + λx, where λ is a constant. How is its capacitance C related to the vacuum capacitance C0?
• Two thin circular rings of radius R each are kept on the same axis with their centres separated by a distance d. One ring carries charge +q and the other carries charge −q. What is the potential difference between the centres of the two rings?

⚔️ Practice JEE Main Physics free + battle 1v1 →