electric fields

Equation for electric force

(1/4pi free space) x (Qq/r²)

F=ma or mg

F=QE or Qv/d

If the electric force is + or -, which is attracting and which is repelling

+=repelling

-=attracting

For electrostatic field lines which direction is a positive atom and negative atom going

+ve is going same way

-ve is going opposite direction to lines

Definition of electric field strength

Force per unit charge exerted on a +ve charge placed at a point

Electric force

Between two point charges, separated by a distance in a vacuum, it is directly proportional to the product of two masses and inversely proportional to Distance squared

Equation for electric field strength

E=F/Q

E=v/d

E=(1\4pi free space) x (Q/r²)

How to find charge if electric field strength is equal to gravitational field strength

Eq=mg

Q(v/d)=mg

Q=mgd/v

How to calculate a point in a distance where the resulant electric force = 0

Q1/x² = Q2/(dist-x)²

Flip and square root

Cross multiply and solve

What is the motion of an electron through a electric field

Electron starts right angle to field lines

Then goes in a parabolic curve heading downwards

What is electric potential

The work done per unit charge in bringing a small +ve test charge from infinity to a point

Equation for electric potential

(1/4pi free space) x Q/r=V

Change in Wd / Q=V

Change in Ep/Q=V

Equation to find the change in Wd

Q x change in V

(1\4pi free space)(Qq)(1/r1 - 1/r2)

Work is done against the field when…

Like charges approach and opposite charges recede

Therefore Ep increases

Work is done by the field when…

Opposite charges approach and like charges recede

Therefore Ep decreases

What happens when a charge moves from inner to outer equipotential surface

Work is done

What happens when a charge travels within the same equipotential surface/constant potential

No work is done

How do you find electric potential at a point in a shape

Think of it like the distance are vectors

Use the electric potential equation to find the electric potential from that distance

Add them up just like vectors to get the electric potential at the point you r heading to

What is the direction of electric potential in field lines

Opposite direction to field lines, so you would basically do V2-V1