Circuits Flashcards
Not again :( (21 cards)
Define Ohm’s law
Ohm’s law is a method used to find the voltage of a circuit.
Voltage= current x resistance
Commonly known as:
V=IR
Fill in this diagram
The structure of an atom
Nucleus- positively charged
Electrons- negatively charged
What happens when you rub a cloth against a polythene rod?
When rubbed together friction causes some electrons on the cloth to be knocked off atoms.
These electrons stick to the atoms of the polythene rod.
As electrons have a negative charge (-) the polythene rod gains a negative charge.
As the cloth has lost the electrons negative charge (-) the cloth gains a positive charge.
What are the rules for forces between charges?
+ attracts -
- repels -
+ repels +
What is the job of a cell in a circuit?
It provides an electrical current
What is an electric current
An electric current is the flow of electrons from the negative end to the positive end of the power source.
How do you calculate the total resistance in a series circuit?
Add up the individual resistance from each resistor. For instance if a series circuit had two resistors- one was 7 Ω and one was 2Ω then the total resistance would be 9Ω.
What is charging?
The movement of electrons between objects
How do you measure electric current using an ammeter?
Connect the ammeter in series to the component or part of the circuit you want to measure.
What is a series circuit?
In a series circuit, if a lamp breaks or a component is disconnected, the circuit is broken and all the components stop working.
A series circuit has all the components in one loop connected by wires, so there is only one route for current to flow.
What are the rules for current in a series circuit?
-Current is the same through each component.
-If a lamp breaks or a component is disconnected, the circuit is broken and all the components stop working.
-The total voltage of the power supply is shared between the components.
What is a parallel circuit?
A parallel circuit is way of connecting components on separate branches, so the current can take different routes around the circuit.
btw: adding more components to a parallel circuit decreases the total
resistance
What are the rules for current in a parallel circuit?
The current in a parallel circuit splits into different branches then combines again before it goes back into the supply.
When the current splits, the current in each branch after the split adds up to the same as the current before the split.
What are the rules for voltage in a series circuit?
-Must be connected in parallel to components
-The total supplied voltage is shared between components in a series circuit
-Adding all of the voltages across all of the components together would find the total supplied voltage
-If one component has twice as much resistance as the other, the voltage across the higher resistance component is double the voltage across the lower resistance component
What are the rules for voltage in a parallel circuit?
The voltage across components connected in parallel is the same as the supply voltage for each component.
Define electrical resistance and explain how to calculate it.
Anything in the circuit that slows down the flow of current. Resistance= voltage ÷ current
What are fuses?
The fuse breaks the circuit if a fault in an appliance causes too much current to flow. This protects the wiring and the appliance if something goes wrong. The fuse contains a piece of wire that melts easily. If the current going through the fuse is too great, the wire heats up until it melts and breaks the circuit.
How do fuses improve safety?
If a fuse is missing, it can lead to several dangerous outcomes, including the potential for fires, damage to electrical equipment, and injury
What is the heating effect of electrical current?
The heating effect occurs when an electric current flows through a conductor with resistance, generating heat. This happens because the movement of electrons (the current) encounters resistance within the material, and some of the electrical energy is converted into thermal energy.
What is the voltage rule for cells connected in series?
Their individual voltages add up to create the total voltage of the battery or circuit.
