A spherical, non-conducting shell of inner radius r1 = 10 cm and outer radius r2 = 15 cm carries a total charge Q = 15 μC distributed uniformly throughout its volume. What is the electric field at a distance r = 12 cm from the center of the shell?

E = 2.87 * 10⁶ N/C

Explanation:

Electric Field Intensity Formula E = K q / r²

We will first find the charge density according the given data. (After that we will find charge enclosed by r=12 cm)

r₁ = 10 cm = 0.1 m, r₂ = 15 cm = 0.15 m, Q = 15 μC = 15 * 10⁻⁶C

charge density = Charge enclosed / volume

Volume shell = 4/3 π (r₂³ - r₁³) = 4/3 π (0.15³ - 0.10³) = 9.948 * 10⁻³ m³

charge density = 15 * 10⁻⁶C / 9.948 * 10⁻³ m³ = 1.51 * 10⁻³ C / m³

Now the Volume of shell at (r=12 cm =.12 m) = 4/3 π (0.12³ - 0.10³) = 3.049 * 10⁻³ m³

Now the amount of charge inside r=0.12 m which is

Charge = Charge density * volume = 0.151 * 10⁻³ C / m³ * 3.049 * 10⁻³ m³

=4.60 * 10⁻⁶ C

So E = 8.99 * 10 ⁹ N m²/C * 4.60 * 10⁻⁶ C / (0.12 m) ² = 2.87 * 10⁶ N/C