electric field due to pt charge and extended bodies

Question 1

electric field due to a point charge

Answer 1

Kq/x^2

Question 2

electric field due to uniformly charged rod AT AXIAL POINT

Answer 2

KQ/L [1/R + 1/(R+L)]

L is length of rod and R is distance from the end

Question 3

electric field at an equatorial point of uniformly charged rod

Answer 3

2KQ/[R√(L² + 4R²)]

L is rod length R is perpendicular distance from centre of rod

Question 4

field due to uniformly charged infinite thread

Answer 4

2Kλ/r

where λ is linear charge density C/m
r is perp. distance from the thread

Question 5

field due to uniformly charged semi-infinite thread (infinite from one end and the point is perpendicular right to the other end so there is no symmetry involved)

Answer 5

√2Kλ/r

r is perp. distance from one end of the thread
pls look up this derivation its long asf

Question 6

field at general point due to a uniformly charged rod

Answer 6

2Kλ/r

where r is perpendicular distance from rod at any point

Question 7

electric field due to uniformly charged ring

Answer 7

at axial point-
KQx/[(R² + x²)^3/2]

0 at centre
when it is cut, E= KQw/2piR^3 where w is the width of the cut portion

Question 8

field due to uniformly charged circular arc

Answer 8

2KQsin(θ/2)
θR^2

R is radius of the arc
this can be used for half ring by putting pi and quarter ring by putting pi/2