How Do You Calculate the Electric Field from an Arc?

[VitaX]

Homework Statement

Homework Equations

E = k*Q/r^2

The Attempt at a Solution

I tried to get the factor through integrating, but it was wrong.I ended up with (k*lambda*2)/R multiplied by the integral of cos(theta) dtheta. Limits were 10pi/21 and 0. I then divided by k*Q/r^2.

 

[SammyS]

0 to 2π is a complete circle.

The arc appears to be symmetric WRT the x-axis, ∴ integrate cosθ from ‒10π/21 to 10π/21 , which should give twice the answer you had.

 

[VitaX]

Is theta/sin(theta) the answer to this problem? theta being in radians and half the angle of the arc.

 

[SammyS]

Is theta/sin(theta) the answer to this problem? theta being in radians and half the angle of the arc.

I'm sorry, I only looked at your integral in my earlier post. The 2 in the factor preceding your integral makes up for only integrating over half the arc.

Depending upon what you are using for θ, your answer of θ/sinθ looks good.