Physics Electricity Jan 2018 Flashcards
What is resistance?
Resistance is how difficult it is for electrons/current to flow
What happens when there is a low resistance?
There is a greater flow of current
What equation do you use for Resistance?
V = I/R
What is Voltage?
Voltage is the energy per unit charge(think of it as the energy carried by the electrons)
What is current?
Current is the rate of flow of charge
What happens to the voltage and current in a series circuit?
The voltages add up and the current stays the same
What happens to the voltage and current in a parallel circuit?
The voltage is the same and the current adds up(remember traffic)
The resistance of a wire is directly proportional to the ……. of the wire
Length
The resistance of a wire is inversely proportional to the ……. of a wire
Thickness
What is the equation used for current / charge?
I = Q / t or Q = It
What is the unit for charge?
Coulombs
What is the equation for voltage?
V = (W or E) / Q
What are the 3 wires in a plug?
The earth, neutral and live.
What is the purpose of the earth wire?
To carry charge away from the applicance to the ground when an accident occurs. Acts as as safety measure.
What is the purpose of the neutral wire?
To carry charge away from the appliance and complete the circuit.
What is the purpose of the live wire?
The live wire carries the 230 V charge towards the appliance but can be dangerous when not attached properly. (Hence why the earth wire is needed)
What is the purpose of the fuse?
To blow the circuit when a certain amplitude is reached. This is a safety measure so that the appliance doesn’t become dangerous.
What type of appliances need double insulation? Why?
Plastic appliances need two core cables because there is no earth wire.
What is the definition of frequency?
The amount of cycles per second
What is the definition of time period?
The time taken to complete 1 full cycle
What is the equation for frequency?
f = 1/T
What is the equation for time period?
T = 1/f
What does ‘AC’ stand for? what is it?
‘AC’ stands for alternating current and is a type of electrical current in which the flow of current changes from one direction to the other.
What is the mains supply?
The mains supply is the general-purpose alternating-current (AC) electric power supply
What does ‘DC’ stand for? what is it?
‘DC’ stands for direct current and is a type of electrical current in which the flow of current always flows in the same direction.
What is Ohm’s Law?
Ohm’s Law is the current is directly proportional to the voltage at a constant temperature.
What happens when there is a high resistance?
There is a smaller flow of current
What do field lines show us?
The direction of the field (e.g. from positive to negative) and the strength of the field
What are field lines used for?
To represent an electric field.
What is the definition of an electric field?
An electric field is a region in which charges (positive or negative) feel a charge.
