1951

Physics Electrostatics Level: High School

A thin rod of length l and uniform charge per unit length lamda lies along the x axis , as shown in the figure at ‘click here’ .

a) Show that the electric field at P , a distance y from the rod along its perpendicular bisector , has no x component and is given by E = 2ke lamda sin theta 0 / y .

b) Using your result to part (a), show that the field of a rod of infinite length is E = 2ke lamda / y .

(Hint : Calculate the field at P due to an element of length dx , which has a charge lamda dx . Then change variables from x to theta , using the relationships x = y tan theta and integrate over theta .)