Electricity and Magnetism Flashcards
What is Electrical Energy? (3 Main Points)
- Electrical energy is a type of kinetic energy.
- The movement of electrons from negative to positive (because electrons have a negative charge).
- It is a convenient form of energy because it can easily be changed into other forms of energy like light and sound.
What is Current Electricity ?
Current electricity is the flow of electrons through a electrical conductor.
What is Static Electricity?
Static electricity occurs when charges collect on surfaces (insulators) and do not flow away immediately
What are Conductors? (2 Main Points)
- In some materials, called conductors, some of the electrons are free to leave.
- They can flow through the conductor in an electric current.
What are Insulators? (2 Main Points)
- In other materials, called insulators, the electrons are tightly held and cannot leave.
- Electrical current will not flow but static electricity can build up.
What happens to the charge of objects when they are rubbed together, and how do charges interact?
Rubbing transfers electrons: gain = negative charge, lose = positive charge. Opposite charges attract; like charges repel.
What is the Danger of Static Electricity
- Static sparks near petrol can ignite fumes, causing fires.
- Lightning rods protect buildings by safely directing static charges from lightning into the ground.
What are the uses of Static Electricity?
Photocopiers, Defibrilatiors, and Printers
What are the three components of Electrical Circuits?
- An energy supply - cell or a battery of cells
- A component to transfer electrical energy into another form - e.g light bulb
- A complete & unbroken pathway for the electrons to flow - usually made of copper wires
What is Current? (3 Main Points)
- Current is a measure of flow of electrical charge in a circuit
- Current is measured in amps (A) using an ammeter
- Ammeters must be connected in series
What is Conventional Current?
Before the discovery of electrons, scientists thought that current was the movement of positively charged from the positive to the negative terminal.
What is Electron Flow defined as?
Charge carried by electrons from the neg (-) to the pos (+) terminal.
Define the Current in Series? (2 Main Points)
- In a series circuit, current flows through one continuous pathway
- The current is the same in all parts of a series circuit
Define the Current in Parallel? (2 Main Points)
- In a parallel circuit, the current divides at the point where the circuit branches and then recombines to complete the circuit.
- The current is shared between branches in a parallel circuit.
What is the Voltage? (4 Main Points)
- Voltage is the energy (or “push”) for electrons to flow in a circuit.
- It’s the difference in electrical potential between two points, also called potential difference.
- Adding batteries increases voltage.
- Measured in volts (V) using a voltmeter, which connects in parallel.
What is Voltage in Series? (3 Main Points)
- Voltage is shared across components.
- Identical bulbs are equally but dimmer lit.
- Total voltage equals battery voltage.
What is Voltage in Parallel? (2 Main Points)
- Voltage is the same across all components, matching the battery voltage.
- All bulbs will have equal brightness.
Define and State what Power is?
Power is how much energy (in joules) is transferred from one form to another in one second
What was Power measured in?
Watts (W)
What are the two ways of calculating power in this topic?
Power = Energy/Time
or
Power = Current x Voltage
What do the Power Triangles look like
1) Energy (E) at the top, Power (P) on the left, Time (T) on the right
2) Power (P) at the top, Current (I) on the left, Voltage (V) on the right
How to calculate KWh
kW x hours
Why is Electricity Dangerous? (3 Main Points)
- Warning signs indicate high voltage.
- Electric shocks can disrupt nerve signals, causing serious health issues.
- Faulty appliances may lead to electrical fires.
What is Resistance Defined as?
- Resistance is a measure of how easy it is for current to flow in a circuit
- Higher resistance = lower current flow.
What are the three magnetic materials?
Magnetic materials must contain iron (Fe), cobalt (Co), or nickel (Ni)
What are the 3 Main Points of Magnets?
- Magnets are surrounded by invisible magnetic fields
- The magnetic field exerts a non-contact force on magnetic objects
- The field is strongest at the North pole and South pole
Define the Magnetic Attraction
- Opposite poles attract (are pulled together).
- Same poles repel (push away from each other)
What is the Law of Magnetism?
The Law of Magnetism states that like poles repel each other, while opposite poles attract.
Define the state of inside a magnet (3 Points)
- Inside magnetic material there are small regions called “domains”.
- In magnets, these domains can line up and face the same way
- This gives the material an overall magnetic polarity
How do you destroy a magnet?
Striking the magnet with a hammer or heating it
Describe how could determine the strength of a magnet.
Count how many paper clips it is able to hold, end on end.
Describe how you could make a magnet (magnetise an object).
Rub the metal object with a magnet (but only in the same direction)
Describe how electricity and magnetism are linked.
When electrical charges flow in a wire, a magnetic field is formed around the wire. Electricity is a type of energy and magnetism is a type of force
Name the three parts that make up a simple electromagnet. You may include a diagram in your answer.
An electromagnet consists of core of magnetic material (such as iron) surrounded by a wire coil, through which an electric current is passed.
List three factors that affect the strength of a simple electromagnet.
- Number of wire coils
- Magnitude of electric current
- Size of iron core
Why are electromagnets and not bar magnets used in scrapyards?
You can switch them on and off
Give two other uses of electromagnets.
- Doorbells
- Electric Motors
