Electric FIelds Flashcards
Describe an electric field around a charged object
Measured in coulombs
Positive or negative
If a sphere, charge is towards the centre
Describe the direction of force ona charges that are repulsive or attractive
Attractive - Opposite forces , so force is negative
Repulsive - Same forces , F will be positive
What iselectric field strength
Force per unit charge.
NC^-1
Field lines For +ve Q , point away
Field lines for -ve Q, point towards
Describe the electric field for a radial field
E=kQ / r^2
Inverse square law.
Field strength decreases the further away from Q
Describe the Electric field for a uniform fields
Parralel plates ,E is the same at all points between plates.
E = V/D
Describe the path when a charged particle enters an electrric field
Enters at right angles.
Constant force parallel
+ve - act in same direction
-ve act in opposite direction
Cause particle to accelerate , follows a curved path (parabola)
WHat is Electric potential
Potential energy per unit charge on a point charge from infinity to a point in the electric field.
Absolute Electric Potential greatest on surface of charge, decrease as distance increases,
Infinity will be 0v
What is electric Potential difference
The energy needed to move a unit charge.
FD=QV
What does the tangent of a V against R graph show
Field strength
What do you get from the area under a E against R graph
Change in Electric Potential
What do you get from the area under a E against R graph
Change in Electric Potential
What are equipotentials
Points of equal potential in a field
No work is done along this
What are similarities between gravitational and electric fields
Field lines in radial field point towards the centre.
Field lines in uniform fields are parallel and separated equally
Potential energy at 0 is at infinity
What is the main difference between gravitational fields and electric fields
Gravitational fields are always attractive
where electric forces can be either attractive or repulsive
