Sol: Given  A) Electric field E = 10000 N/C Distance r = 0.5 m We know that due to point charge electric field at a distance r is  E = kQ /r²........................(1) Where  K = 9*10^9 Nm²/C² So, from equation(1) Q = Er²/k     = (10000)(0.5)²/(9*10^9)     = 2.77777*10^-7      = 277.8*10^-9 C     ≈ 277.8 nC B) Force F = 100 N Distance r = 0.4 m We have force F = kQ1Q2/r² But here given identical charges  so Q1=Q2 = Q F = kQ²/r² Q ... See the full answer