yr 2 - electrical fields

What does the direction of the field lines represent?

The direction of the force acting on a positive test charge

Electrical field strength??

• Force / unit charge

  • Or also E=kq/r²

  • Where k= 9×10⁹

Coulomb’s law ?

• The product of the two charges is directly proportional to the force of attraction/repulsion but inversely proportional to the square of the distance between them

  • F = kQ1Q2 /r²

Electrical potential ?

The work done to take a positive test charge from infinity to a point

• V= wd/q

Electrical potential in a radial field??

Here we use V= kQ/r

• we add in the sign of the charge here

Field line properties?

• Parallel and evenly spaced (uniform)

• the concentration across the field lines is equal

• goes from + to -

• acceleration of electrons in the field is equal

• on a positive test charge the lines go outwards

Equipotential surface?

Point at which zero work is done to overcome to force of attraction/#

follows the shape of the plates and should be perpendicular to the field lines

Potential gradient?

w = f x d and E = f/q so if f = qe then w= qe x d, we know w/q is V so V= Ed and therefore V/d is the potential gradient