A uniformly charged conducting sphere of \( 1.6\,\mathrm{m} \) diameter has a surface charge density of \( 60\,\mu\mathrm{C\,m^{-2}} \). The total charge on the sphere is
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → \( 4.8\times10^{-4}\,\mathrm{C} \)
The surface charge density is charge per unit area, so the total charge is \( Q = \sigma \times 4\pi r^{2} \), where \( r \) is the radius (half the given diameter).
\( r = 1.6/2 = 0.8\,\mathrm{m} \)
\( \sigma = 60\,\mu\mathrm{C\,m^{-2}} = 60\times10^{-6}\,\mathrm{C\,m^{-2}} \)
\( 4\pi r^{2} = 4\times3.14\times(0.8)^{2} = 8.04\,\mathrm{m^{2}} \)
\( Q = (60\times10^{-6})(8.04) = 4.8\times10^{-4}\,\mathrm{C} \)
Note: NTA picked this question from an NCERT (2026-27) exercise and changed the figures. Do not ignore NCERT while practising numericals.
NCERT (2026-27):
Exercises – …
