P3 Flashcards
Give the definition of static electricity
Static electricity- electric change that has accumulated on an object but is stationary due to the objects inability to conduct
Give an example of when static electricity might occur
An example of when static electricity occurs is when two objects that are not good conductors are rubbed together such as a balloon against your hair could rub electrons onto the balloon giving it a negative static electric charge
What will objects carrying opposite charges experience?
Objects carrying opposite charges experience a force of attraction
What is an electrical field?
An electrical field is a region round a charged object where a force would be exerted on other objects
Which way do field line arrows point?
Field line arrows point in the way a nearby positively charged object would be attracted
What happens when the electric fields of two charged objects interact?
When the electric fields of two charged objects interact a force is produced.
Use the flash cards in the back of phone case to correctly identify all the circuit symbols
Good luck 😊
😊😊
Give the definition of resistance
Resistance is the potential difference (energy) needed to drive a current round a circuit
Resistance =
Resistance= potential difference/ current
What sort of effect does temperature have on resistance and why?
Temperature causes the resistance to increase because it decreased the current because the atoms have more energy and vibrate making it harder for the electrons to pass through
Sketch the potential difference current graph of a resistor and describe why it has this shape
A potential difference- current graph of a resistor has a linear shape passing through 0 because potential difference is directly proportional to current at a constant temperature
Sketch the potential difference current graph of a filament lamp and describe why it has this shape
The potential difference - current graph of a filament lamp curved because as the current increases it increases the temperature of the lamp which increases the resistance thus either decreasing the current or increasing the potential difference
Sketch the potential difference current graph of a diode and describe why it has this shape
A potential difference - current graph of a diode is flat on the left because current will only flow in one direction because of the high resistance in the opposite direction.
Name two things you must remember when using an ammeter in a circuit
1) the ammeter must be placed in series with the component
2) the ammeter cannot be parallel to the voltmeter
Name one thing you must remember when using a voltmeter in a circuit
1) the voltmeter must be in parallel to the component
Explain what a diode is and what it us used for
A diode is a device that only allows current to flow in one direction due to its extremely high resistance in the opposite direction. It is usually made out of a semiconductor such as silicon and used to control currents in circuits such as radio receivers
Explain what a light dependant resistor (LDR) is and what it is used for
A light dependant resistor is a component that values its resistance according to the light intensity.
Low light intensity = high resistance
High light intensity= low resistance
This makes LDR’s ideal for automatic outdoor lights because during the day the resistance will drop so the PD will also drop not supplying much energy to the lamp and at night the resistance will raise which will cause the PD to increase supplying more energy
Explain what a thermostat is and what they are used for?
A thermostat is a component which varies its resistance depending on the temperature
High temp= low resistance (so less pd is supplied to heater)
Low temp= high resistance(so more pd is supplied to heater)
This makes thermistors ideal for thermostats
Give the definition of current and units
Current is the rate of flow of electrons around a circuit
Units- amps
Give the definition of charge
Charge is the amount of electrical energy contained in an object, particle or region of space
Unit - coulomb
Charge=
Current x time
Give the definition and units of potential difference
Potential difference us the difference in electrical potential difference between ten points in a circuit that makes an electric current/ charge move
Units- volts
Potential difference =
=
Potential difference=Energy transferred / charge
Potential difference =current x resistance
How are current and resistance linked to potential difference
Resistance increases with current because current creates heat which increases resistance. A higher resistance means more energy is needed so the potential difference of battery needs to be greater
Give the definition of power
Power is the measure of energy transferred per second through a component
Power=
Power=
Power=
Power= energy/ time Power= potential difference x current Power= current 2 x resistance
What is a series circuit?
A series circuit is a circuit with only one branch so the current has only one pathway
What is the rule for the current in a series circuit?
The current is the same anywhere in a series circuit
What is the rule for the potential difference in a series circuit?
The potential difference is shared between all the components in a series circuit so the pd across the component will add to the pd across the power supply
What is the rule for the resistance in a series circuit?
In a series circuit the resistors add up to the total resistance
What us the rule for current in a parallel circuit?
The current in a parallel circuit is shared between branches which add up to the current leaving the cell
What is the rule for potential difference in parallel circuits?
Potential difference is the same on each branch of a parallel circuit
What is the rule for resistance in a parallel circuit
The total resistance of a parallel circuit is less than the resistance of the smallest resistor
How can you investigate potential difference in series and parallel circuits?
To investigate potential difference in series and parallel circuits set up a circuit with a power pack, voltmeter and bulb. First ad bulbs in series they should get dimmer as the pd is shared across the branch. Aging bulbs in parallel will not make them get dimmer
