Practice question

Given: A thin spherical shell of radius 25 cm has a charge of 15 μC . What is the electric field at a point 30 cm from the nter? These values define the system as per NCERT data. Formula: Outside shell ( r > R ): E = k q/r². This is the standard NCERT relation for this phenomenon. Substitution & Calculation: k = 9 × 10⁹ Nm²/C², q = 15 × 10⁻⁶ C, r = 0.3 m . E = 9 × 10⁹ × frac15 × 10⁻⁶(0.3)² = 9 × 10⁹ × frac15 × 10⁻⁶⁰.09 = 1.5 × 10⁶ N/C . Result: The computed value matches the expected outcome and confirms the correct choice. Units and powers like J kg⁻¹ K⁻¹, m/s², 10⁻⁵ are properly used as per NCERT.