Practice portal › Electric Charge and Properties › Electric Field of Point Charges
Asked in GUJCET 2013 · Field of discrete charges
Given: q₁=10⁻⁹ C at (0,0,0); Q at (2,0,0); field point P(3,1,1).
Idea: the field of a point charge is ⃗E=(kq ⃗r)/(r³), with ⃗r drawn from the charge to P, so its y-component is (kq y)/(r³).
From q₁: ⃗r₁=(3,1,1), r₁=√11, so E_1y=(k(10⁻⁹)(1))/(11^3/2)
From Q: ⃗r₂=(1,1,1), r₂=√3, so E_2y=(kQ(1))/(3^3/2)
Set E_1y+E_2y=0: (10⁻⁹)/(11^3/2)+Q/(3^3/2)=0
Q=-10⁻⁹(3/(11))^3/2=-10⁻⁹×0.1424
Q=-0.1424×10⁻⁹ C
Reading this solution needs no sign-in. You only sign in to practise against the clock and keep your progress.
Practise this with a timer