Answer:
3 a is the ans i think so ....
As per the given Figure attached here we know that both charges q1 and q2 will apply same force on charge q3 and hence the resultant force due to both charges will be along Y axis vertically upwards
So here we know that

now from the above equation


so both of the charges will apply 0.288 N force on q3 charge along the line joining them
now the net force due to vector sum is given by

here we know that angle is

now we have


so net force on q3 is 0.46 N vertically upwards along +Y axis
Answer:
E = 2k 
Explanation:
Gauss's law states that the electric flux equals the wax charge between the dielectric permeability.
We must define a Gaussian surface that takes advantage of the symmetry of the problem, let's use a cylinder with the faces perpendicular to the line of charge. Therefore the angle between the cylinder side area has the same direction of the electric field which is radial.
Ф = ∫ E . dA = E ∫ dA = q_{int} /ε₀
tells us that the linear charge density is
λ = q_ {int} /l
q_ {int} = l λ
we substitute
E A = l λ /ε₀
is area of cylinder is
A = 2π r l
we substitute
E =
E =
the amount
k = 1 / 4πε₀
E = 2k 