Circuits and Static electricity Flashcards
What is current?
a rate of flow of charge
What is resistance?
a measure of how easy or difficult it is for the current to flow
What is charge?
A property of matter that causes it to be positive or negative.
What is potential difference?
How much energy is needed by a charge to push the current through the circuit.
Equation for charge
charge(coulombs/ c) = current x time(s)
(Q = I x T)
Equation of potential difference
Potential difference = current x resistance
(V = I x R)
What is resistance measured in?
Ohms
What is the relationship between the length of the wire and the resistance of the circuit?
It is directly proportional. When the length increases, the resistance increases too. The longer a piece of wire is, the more difficult it is for the current to flow. The graph is a straight line through the origin.
What are electrical insulators?
Meterials with extremely high resistance
What is the relationship between current and potential difference for a fixed resistor?
A straight line through the orgin, directly proportional. As the current increases, the potential difference increases. The resistance remains constant as the current changes. It means that it is an ohmic conductor.
What is the relationship between the current and potential difference for a lamp?
The graph is a curve. The resistance of the bulb increases as the current and the potential difference increases. This is because the bulb gets hotter as more current flows through it and the temperature of it increases.
What is the relationship between resistance and temperature for a thermistor?
what are thermistors used for?
resistance decreases as temperature increases, used in thermometers, thermostats, electric kettles etc.
What is the relationship between resistance and light intensity for a LDR?
What are LDRs used for?
resistance of LDR decreases when light intensity increases, used in light sensors and street lamps
Rules of current, p.d. and resistance for series circuits
- Current: current is the same everywhere
- P.d: p.d. of power supply is shared between the components
- Resistance: the total resistance of the circuit is the sum of all of the individual resistances
Rules of current, p.d., and resistance in parallel circuits
- Current: splits when it reaches a junction
- P.d. is the same in each branch
- Resistance: the more routes you provide for the current to flow, the easier it is for the current to flow though
What is the relationship between the current and potential difference for a diode?
- graph is a curve
- resistance decreases as the current and p.d. increase
- no current can flow when it is turned around as the resistance is too high
What is static electricty?
- charge that builds up because it is not able to flow away into the surroundings
- electrons become static in movement
How can objects be charged?
- when electrons are transferred to or from an object
what happens when the material gains electrons?
- becomes negatively charged
What happens when the material loses electrons?
- gains a positive charge
What causes sparks?
- when electrons discharge to a conducting material or to the ground through the air
- the object becomes discharged or earthed
How are electric fields drawn?
- from positive to negative
- stronger field= more field lines
- spread from single point
Draw all of the circuit symbols
notability! :3
