1) Equal charges q each are placed at the vertices of an equilateral triangle of side r. The magnitude of electric field intensity at any vertex is A) 2q4πϵ0r2 B) q4πϵ0r2 C) √3q4πϵ0r2 D) √2q4πϵ0r2 Answer: Option CExplanation: Due to charge at A and B magnitude of intensity of electric field at point C E1=E2=14πϵ0.qr2 Net intensity at point C is ER=√E21+E22+2E1E2cos600 ER=√E21+E22+2E21×12=√3E1=√3q4πϵ0r2