Find electric Field at a point A

[FJay]

Hi Guys,
I've been learning electric field, and i want to ask about this question.EF net = EF1 + EF2

my EF1 = 9 x 10⁹ * 4 x 10^-8 / (0.6)² = 1 x 10³ (From Q1)
EF2 = 9 x 10⁹ * 2 x 10^-8 / (0.3)² = 2 x 10³ (From Q2)

then EFnet = (2+1) x 10³ = 3 x 10³

and what i get from key answer is 2.2 x 10³

and anyone can tell me what i miss ?

 

[DrClaude]

The electric field is a vector quantity. What is its (vector) value at A?

 

[FJay]

The electric field is a vector quantity. What is its (vector) value at A?

Enet = (E1² + E2²)^1/2

Enet = 2.23 x 10³

do you mean like that bro ? anything wrong from my answer ?

then for another question like this( at different point), just do this step ?

 

[DrClaude]

Enet = (E1E2² + E2²)^1/2

Enet = 2.23 x 10³

There is a typo in the first equation, but otherwise this is correct.

then for another question like this( at different point), just do this step ?

Yes. You first calculate the electric field itself, as a vector, and then calculate the magnitude of the vector to get the magnitude of the field.

 

[FJay]

Yes. You first calculate the electric field itself, as a vector, and then calculate the magnitude of the vector to get the magnitude of the field.

Thank you for your help.