P3 Electricity Flashcards
Like charges…
Repel
Opposite charges…
Attract
If there is a difference between the charges of two objects…
There is a potential difference between the two objects
Rubbing an object against another object can cause…
Electrons to jump from one object to another (both objects become charged)
A charged balloon can move water falling from a tap. Why is this?
The charge on the balloon attracts or repels the electrons in water
What is the result of a potential difference between two objects?
Rapid transfer of charge
Static electricity arises when…
This results in…
Electrons transfer from one object to another
One positively charged object and one negatively charged - there will be an electric field between the objects
Charged objects create ____ ____ around themselves
Electric fields
The direction of an electric field is…
The direction that a positively charged object would move at that point in the field
Two factors affect the strength of the electric field:
The closer an object is to the charged object, the stronger the field
The higher the charge of the object, the stronger the field
Current is…
The rate of flow of electric charge
For an electric charge to flow there are two essential factors:
Potential difference
Closed circuit
A ___ has ____ value at every point in a closed loop
Current
The same
Ammeters measure…
The flow of current that passes through it
Ammeters have to be connected in ____ (in the same loop of the circuit) with the electrical component whose current you are measuring
Series
Potential difference is…
The amount of energy per unit charge
We say an object is uncharged / neutral when…
It has equal amounts of protons and electrons
An electric field is…
A region around a charged object, in which another charge object will experience a force
Describe the current in a series circuit
In a series circuit the current at every point is the same
Describe the current in a parallel circuit
In a parallel circuit, the current from the source is the sum of the currents in each branch
Potential difference is measured using a…
Voltmeter
A voltmeter is always placed…
In parallel across the component whose pd we want to measure
Define resistance
The property of a material to resist the flow of electrical current due to collisions of free electrons
Resistance is measured in…
Ohms
Define conductor
Something that allows electricity to flow through it
Define insulator
Something that does not allow electricity to flow through it
Power is…
A measure of how much energy is transformed per second
Resistance is ____ to length of wire
Directly proportional
As length of wire doubles, resistance…
This is because…
Also doubles
Because there is twice the material to pass through, so it is twice as difficult
A diode…
Only allows current to flow in one direction
How does light intensity affect the resistance of an LDR?
As brightness increases resistance decreases (not linear)
