Electricity (4) Flashcards
What is matter made from?
Atoms.
What happens to an atom when it loses electrons?
It becomes positively charged.
What happens to an atom when it gains electrons?
It becomes negatively charged.
What does each electron carry?
A tiny charge (Q).
What is the unit for charge?
Coulomb (C).
How do we measure a unit of charge of an electron?
We bundle billions of electrons into a coulomb.
What is electric current?
It’s the number of coulombs of charge passing a point each second.
What is the symbol for current?
I.
What is the unit of current?
Amperes (A)
What would 3C of charge passing through a bulb in 1 second be when translated into amperes?
3A.
What is the formula for charge?
Q=It.
Where could you find an electrical force field?
Around charged particles.
What does the direction of an electric field mean?
It is the direction a positive particle would travel if placed in the field.
What is electrical energy that a coulomb of charge is defined by?
Voltage/potential.
What is the difference between the voltage/potential a coulomb has at one point or another?
It is called the potential difference (p.d.)
What is potential difference measured in?
Volts.
What does the voltage of a cell tell you?
The amount of energy the cell gives you or transfers to each coulomb of charge.
What do coulombs do?
They carry the energy around a circuit.
What is the voltage across a component?
It is the amount of energy a coulomb gives up at the component.
What is energy measured in?
Joules
How does d.c. from d.c. battery travel in a circuit?
The current is a constant size and travels in one direction from the negative side of the battery to the positive side.
How does a.c. from a.c. battery travel in a circuit?
The current changes size and direction continually.
How does a.c. travel in British homes?
The current changes direction in kettles and TVs 50 times each second (frequency 50 Hz).
What things have a d.c. supply?
Car battery and watch battery.
What things have a a.c. supply?
Electricity in your house.
What is used to measure current?
Ammeter.
What does the ammeter measure exactly?
The number of coulombs passing a point each second.
What is used to measure voltage?
Voltmeter.
What do all materials do in terms of resistance?
All materials oppose the flow of current (this is called resistance).
What are the units for resistance?
Ohms.
What happens as the resistance of a circuit increase?
The coulombs find it more difficult to flow meaning the current in a circuit decreases.
How does the temperature of a component affect the resistance?
The higher the temperature the higher the resistance meaning the lower the current that is passing through.
How does current act in a series circuit?
As there is only one path for the current to travel it stays the same all the time.
How does voltage act in a series circuit?
The voltage across the whole circuit adds up to the supply voltage.
How does current in a parallel circuit travel?
As there are multiple branches current travels through them until reaching the same current as the one that is in the supply.
Where does electricity first flow in a parallel circuit?
The waves travel to the first available branch meaning more of the current will split off to this branch.
What stays the same no matter where it is in a parallel circuit?
Voltage, It is equal to the supply voltage (even with resistors)
Where are series circuits used?
Christmas lights (simple, cheap) safety switches on devices (avoid accidentally turning on device).
Where are parallel circuits used?
Ceiling bulbs and plug points.
What is Ohm’s Law?
It is the relationship between the current flowing through a component and the voltage across the component.
What do the letters RT represent?
Total resistance.
