Electric Fields
What is the force between two positively charged objects?
Repulsive
What are the two poles of a magnet?
North
South
What is the force of attraction between any two objects with mass?
Gravity / weight
How are electric and gravitational fields similar?
They both exert forces.
They both have magnitude and direction.
Field strength decreases with distance from the source
Draw a simple electric circuit?
(Cell/battery, a switch, bulb)
A circuit containing a cell/battery, a switch and a bulb
What is the unit of electric charge?
Coulomb (C)
What is the shape of the magnetic field lines around a bar magnet.
Lines going from north to south
Highest density at the poles
What is the direction of the gravitational field around the Earth?
Down
How are magnetic and gravitational fields different?
Gravitational fields are generated by mass. Magnetic fields are generated by magnetic materials
Gravitational fields are always attractive. Magnetic fields can be attractive and repulsive
What is a device that uses electricity to create heat?
Heat
Bulb
(Most electrical applicances)
Draw a diagram showing the electric field lines around a positive charge
Field lines going radially OUTWARDS from the charge
How can you make an electromagnet?
Wrap copper wire around a metal core (iron nail)
Connect the copper wire to a power source and turn it on
Explain why objects fall to the ground
The Earth has mass, therefore has a gravitational field
This attracts other objects with mass towards the Earth's centre, so objects fall towards the ground
Give an example of a device that uses both electric and magnetic fields
Electromagnet
Electric motors
Generators
Transformers
Loudspeakers
Hard drives
MRI machines
Name a use for an electromagnet
Loudspeaker
Motor
Any acceptable answer
What is the difference between a conductor and an insulator?
A conductor conducts electricity.
An insulator does not conduct electricity.
Explain the right-hand grip rule for a current-carrying wire
Align your thumb with the direction of the conventional current (positive to negative) and your fingers will indicate the direction of the magnetic lines of flux.
What is the difference between mass and weight?
Mass is a fundamental measurement of how much matter an object contains.
Weight is a measurement of the gravitational force on an object.
Explain the concept of a field line
A visual representation of a (vector) field
It shows the direction and magnitude of a field at each point in space
How does a compass work?
The needle of the compass is magnetic and free to rotate
The Earth's magnetic field pulls on the needle causing it to align with the Earth's magnetic field lines
One side of the needle points to the magnetic north pole
Explain how lightning occurs
Particles in the cloud rub together (friction)
This causes charged particles (electrons) to move and collect together
Once enough electrons have been gathered, they have enough energy to discharge to the nearest conductor on the ground
Describe Earth's magnetic field and its importance
Draw an appropriate diagram
Protects us from cosmic radiation from the sun
Allows us to use instruments such as compasses to navigate
Allows animals such as birds to navigate
Describe the concept of gravitational potential energy
Gravitational potential energy is energy an object possesses because of its position in a gravitational field.
Compare and contrast the three different types of fields
Any suitable answers
Describe why a current is produced in a circuit when a cell/battery is connected
Battery/cell induces an electric field
The negative side of the battery/cell repels the electrons in the wire, causing them to move
Current is the flow of electrons