Electrical Fields Flashcards
Like charges….
….repel.
Opposite charges….
….attract.
What is an electrical conductor?
An electrical conductor is a material that allows the flow of charged particles through it. They do contain free electrons e.g. a metal
What is an electrical insulator?
An electrical insulator is a material that does not allow the flow of charged particles through it. They do not contain free electrons.
When is an electrical insualtor easy to charge?
Some insulators are easy to charge because their surface atoms lose or gain electrons easily.
What do all charged objects have?
All charged objects have an electrical field around them.
Any two charged objects…
…exert an equal and opposite force on each other.
What does the direction of the electrical field lines surrounding a charge show?
The direction of the electrical field lines surrounding a charge is the direction a free positive test charge would move along.
What is the electrical field strength at a point in the field?
The electrical field strength at a point in the field is the force per unit charge on a positive test charge placed at that point.
What is the units for electrical field strength?
NC⁻¹ or Vm⁻¹
If a positive test charge, Q at a certain point in an electrical field is acted on by force F due to the electrical field, the electric field strength E at that point is given by?
E = F/Q
E = Electrical field strength (NC⁻¹) F = Force due to the electrical field strength on charge Q (N) Q = Positive test charge in the electric field strength (C)
The field lines between two oppositely charged flat conductors are:
- Parallel to each other
- At right angles to the plates
- From the positive plate to the negative plate.
The field between two oppositely charged flat conductors is? Why?
The field between two oppositely charged flat conductors is uniform because the electrical field strength has the same magnitude and direction everywhere between the plates.
This is show by the parallel field lines that are equally spaced.
What equation can we use to calculate the field strength between the oppositely charged conductor plates? (Is this only for uniform fields)
E = V/d
E = Electric field strength (NC⁻¹) V = The potential difference between the plates (V) d = The seperation distance between the plates (m)
What does a greater charge on an object tell you about the strength of the field surrounding it?
The greater charge of the object, the stronger the electric field is.
For a charged metal conductor, the charge on it spread across its surface. The more concentrated the charge on the surface…
…the greater the strength of the electrical field above the surface.
Look ar page364, to see an image of this and what this means.
When a charged object X is moved towards another object Y of the same charge (both positive or negative), describe what is happenining in terms of energy transfer?
The electric potential energy store of object X increases. This is because work is done to overcome the resistive force due to Y’s electric field.
This is the same when a charged object X is moved away from another object Y of the opposite charge as the object is doing work against the attractive force.
In both cases, the charged objects moves against the electric (field lines) so work is done by the electric field on the object. When a charged object moves in the direction of the electric field, its potential energy decreases.
What is electric potential?
The electric potential at a certain position in any electric field is defined as the work done per unit positive charge on a positive test charge, when it is moved from infinity to that position.