Cheatography

# Electrostatics Cheat Sheet by Taneesha

cheatsheet for electrostatics

### Basic notations

 K of vacuum 9 x 109 E electric field q charge r distance between 2 charges a radius of circle V electrical potential due to a point charge U electric potential energy

### Electric field due to point charge

 E = Kq/r2

### E due to a spherical shell of charge

 When point is outside the shell E = Kq/r2 When point is inside the shell E = 0 When point is on the surface E max = Kq/a2
here r is the distance between the centre of the circle and a point outside it

### E due to a noncon­ducting charged sphere

 When point is outside the shell E = Kq/r2 When point is inside the shell E = Kqr/a3 When point is on the surface E max = Kq/a2
here r is the distance between the centre of the circle and a point outside it

### Electrical potential due to point charge

 V = Kq/r

### V due to conducting charged sphere

 When point is outside the shell V = Kq/r when point is inside the shell V = Kq/a when point is on the surface V = Kq/a

### U of a system of charges

 1. 2 point charges - U = Kq1q2/r12 2. 3 point charges - U = K (q1q2/r12 + q2q3/r23 + q1q3/r13)
r12, r23, r13 are all distances between the corres­ponding charges

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