Yr12 Flashcards
How to calculate Current?
Time
What is Charge measured in?
Coulombs
How to calculate Charge?
Current x Time
What is Conventional Current?
Current that flows from positive to negative
What is Electron flow?
Current that flows from negative to positive
What is an electrical insulator?
An electrical insulator’s internal electrons don’t move freely and therefore can’t conduct current
How do you measure Current using an Ammeter?
You put the ammeter in series with what you are measuring
What does current do in a parallel circuit when it splits in to 2 paths?
The current splits in half
Does the current remain the same throughout a series circuit?
Yes
Does the current remain the same throughout a parallel circuit?
No
What is Voltage?
Similar to a push from a battery that makes a flow
What can voltage be alternatively named?
Potential Difference
How do you measure voltage using a Voltmeter?
Put in parallel with what you are measuring
What does Voltage do in a series circuit?
It splits across each resistor
How does voltage behave in a parallel circuit?
Voltage remains the same across each branch of the circuit
What happens to voltage when cells are added in Series?
It increases
What happens to voltage when cells are added in parallel?
Stays constant
What does Ohm’s Law State?
The current through a conductor is Directly Proportional to the Voltage across it provided the temperature is constant
What is a Non-Ohmic resistor?
A conductor which does not give a straight line in a Voltage/Current graph
How to calculate Voltage?
Voltage = Current x Resistance
How to calculate resistance?
Resistance = Voltage
———
Current
What is the definition of Resistance?
Resistance is the opposition of a conductor to a current
What causes resistance?
The heating effect
What is the heating effect?
When current flows through a resistance, electrons collide atoms. Electrons may then lose energy, and atoms gain it, and start vibrating. This creates heat.
How does resistance behave if you place resistors on series?
Resistors act as one large resistor. Eg. 3 resistors in series = 1 large resistor
How does resistance behave if you place resistors in parallel?
The inverse of the sum of the inverse of the resistances acts as one resistance. Eg. 1/R eff= 1/R + 1/R + 1/R
1/R eff= 1/3R
R eff = 1/ 1/3R
R eff = 3 R
What is the definition of Electric Current?
Electric current is the rate of flow of charge
How to calculate Power?
Power = Current x Voltage
How to calculate Energy Changed?
Energy changed = Power (OR IxV) x Time
How to calculate cost of energy?
Energy (kWh)= Power (kW) x Time (h)
Multiply this kWh by cost
What is the function of the Earth wire in a plug?
A safety wire. If short circuit occurs, current flows down earth wire so that casing of plug doesn’t become live and electrocute someone
What is the function of the fuse in a plug?
Designed to melt if too large a current flows through it, so as to protect appliance from catching fire
What is the function of the Live wire in a plug?
Input to the device
What is the function of the Neutral wire in a plug?
Output of the device
What is Double Insulation?
This is for devices that don’t have earth wires. They are completely plastic so that casing can’t become live
How do you know what fuse to use for your appliance?
Calculate what current usually flows through appliance. Choose fuse that melts when it is just above normal current
What is a magnetic field?
This is the region around a magnet, where it has a magnetic effect
What happens when a magnetic material is placed in a magnetic field?
It will experience a force
Is a magnetic field created around a conductor when electric current flows through it? What is this called?
Yes, electromagnetism
If a coil was wrapped around a magnet and current was conducted through it, how would you be able to tell the direction of the Magnetic Field and the Poles of the Magnet?
Right hand grip rule
What is the right hand grip rule?
If you were holding on to a magnet wrapped in electric coil with your right hand, using your fingers to display the direction of current, your thumb will indicate the position of the North Pole
What is the Motor Effect? Give a use of it?
A current carrying conductor in a magnetic field experiences a force. This is how electric motors work
How to calculate energy? (Using Charge and Voltage)
Energy = Charge x Voltage
How to calculate Power? (Using Current and Voltage)
Power = Current x Voltage
