Electrical Circuits Flashcards
Define the Following:
Battery, Cell, and Ammeter.
And describe their symbols.
Battery: The scientific word for two or more cells that are joined together.
1 thin line then 1 thick line repeated twice.
Cell: A chemical path that current can travel along.
1 thin line and 1 thick line.
Ammeter: A device used to measure current.
A circle with an A in it.
Define the following:
Voltmeter, volt, voltage, and current.
And describe voltmeters symbol.
Voltmeter: A device used to measure potential difference.
A circle with a V in it.
Current: The rate of flow of electric charge in a circuit it is measured in amperes.
Volt: The unit is used to measure potential difference. Its symbol is V.
Voltage: Another name for potential difference. For a cell, it is the amount of energy that the cells gives to each electron pushed out into the circuit.
What is an electrical circuit and what is the source of its energy?
Electrical Circuit: Is a path for electric charge to flow along.
What is the source of energy?: Main electricity is used to power circuits but it is unstable so it comes from cells or batteries.
What is the difference between a parallel and series circuit and what is needed in a circuit?
What is needed in a circuit?: Source of energy, a complete loop, a component and no short circuits.
A series circuit has all its component wired in the same loop. The current is the same in all parts of a series circuit.
A parallel circuit contains conjunctions and so there is more than one path for the current. The current divides at the point where the circuit branches and then recombines to complete the circuit. so the current is not the same in all parts of a circuit.
What is current and what is it measured in?
Is a measure of the rate of flow of electric charge in a circuit. Electric charge is measured in coulombs.
The current is measured by an ammeter in amperes (A). An ammeter must be connected in series as it measures the current flowing through it.
What is voltage and what/how is it measured in?
Voltage/potential difference is a measure of the difference in electrical potential energy between two points in a circuit.
The voltage of a battery of cell is a measure of the force or push it gives the current. It is measured in volts (V) using a voltmeter. For example, 1V cells gives 1 joule (J) of energy to each coulombs of charge.
The higher the voltage the more power, e.g. the brighter the lightbulb as there is more force pushing the electric charge through. The more battery the more voltage, therefore the more voltage the more energy.
Side Note: A voltmeter must be connected in parallel circuit as it measures the potential difference across the component.
How do cells and batteries work to produce energy?
Batteries and cells produce energy due to the movement of electrons, current. The cells and batteries provide push to move electrons around. They are not used to make electrons.
A chemical reaction takes place inside the cell, which produces a potential difference (voltage) across the cell. So, chemical reaction in battery -> electrical energy -> flow of electrons -> giving away of electrons.
What is Ohm’s Law?
Ohm’s Law: The current flowing through a component of fixed resistance is directly proportional to the voltage across the component or… Voltage = Current x Resistance (V = IR).
V = I x R (Imagine the triangle with the V at the top and I R on the bottom in that order).
I = Current/amps R = Resistance/ohms V = Volts
What does a resister do to current?
A resister restricts the amount of current.
The higher the resistance the more bigger the voltage needed to make a current flow.
Resistance, R, is the number of volt to make 1 amp flow.
Resistance = Voltage/Current and is measured in ohms.
A current of 0.5A flows through a mains lamp (240V)
Calculate the resistance of the lamp.
R = V/I = 240/0.5 = 480 Ω (Ohms)
Why does a resistor restrict flow?
In series: means that there are more electrons colliding with ions and so resistance increases.
In parallel: increases the number of collisions between electrons and ions but also increases the number of routes that electrons can flow through and so resistance reduces.
What else is there to know about a parallel circuit?
The voltage supplied by the battery is shared by the components. So, the sum of the potential difference across the components equals the battery voltage. As more bulbs are added in series, each bulb has less potential difference and so the bulbs become dimmer.
In a parallel circuit, the potential difference across each bulb is the same as the potential difference across the battery.
This means that all the bulbs have the same brightness, and they are brighter than the same number of bulbs in a series circuit.
However, this also means that the battery will run down faster in a parallel circuit.
