Electric Charges and Field Problems - Numerical 04

 

Suggested answer:

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Let F₁ be the magnitude of the force on charge +4mC due to charge +2mC.

Then,

or F₁ = 1.8N

Again, if F₂ is the magnitude of the force on charge +4mC due to charge +3mC, then

F₂ = 2.7 N

Net horizontal component, F_x = F₂ cos60^o- F₁ cos60^o

or F_x = (2.7) (0.5) - (1.8) (0.5)

= (2.7-1.8) 0.5 N = 0.45 N towards left

Net vertical component in the vertically upward direction,

F_y = F₂ sin60^o+ F₁ sin60^o

= ( 2.7 ) ( 0.866 ) + ( 1.8 ) (0.866 )

= (2.7+1.8) 0.866 N = 3.897 N

= 3.9 N (Rounding off to two significant figures)

Net force is given by

= 3.9 N

(Rounding off to two significant figures)

If q is the angle which F makes with the positive direction of y-axis, then