Point charges 4 c and 2 c are placed at the vertices P and Q of a right angle triangle PQR respectively. Q is the right angle,$PR=2 \times10^{–2}m $ and $QR =10^{–2}m$ . The magnitude and direction of the resultant electric field at c is .........
EP = [k(4 × 10–6)/(PR)2] = [(9 × 109 × 4 × 10–6)/(4 × 10–4)] = 9 ×107 N/C EQ = [k(2 × 10–6)/(QR)2] = [(9 × 109 × 2 × 10–6)/(10–4)] = 18 × 107 N/C in Δ PQR, cos θ = [(10–2)/(2 × 10–2)] = (1/2) i.e. θ = 60° E = √(EP2 + EQ2 + 2EPEQ cos 60) = √[(9 × 107)2 + (18 × 107)2 + {2 × 9 × 107 × 18 × 107 × (1/2)}] = √(81 × 1014 + 324 × 1014 + 162 × 1014) = √(547 × 1014) = 2.38 × 108 N/C tan α = [(EQ sin θ)/(EP + EQ cos θ)] = [(18 × 107 sin 60)/{(9 × 107 + 18 × 107 × cos 60)] = [{(18 × 107 × (√3/2)}/(9 × 107 + 9 × 107)] tan α = (√3/2) α = 40.89°