Question

An electric field E⃗ =100,000ı^N/C causes the 5.0 g point charge in the figure (Figure 1)to hang at a 20° angle.

What is the charge on the ball?

Answer 1

Using force balance on mass in vertical direction

T = Tension in rope

In x-direction

Fx = T*sin A = q*E

In y-direction

Fy = T*cos A = m*g

divide both equation

tan A = q*E/(m*g)

q = (m*g*tan A)/E

Using given values:

q = (5.0*10^-3*9.81*tan 20 deg)/100000

q = 1.78*10^-7 C = Charge on the ball

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