TOPIC 2 Electricity Flashcards
What are the types of charges that can move
The only charges that can be moved are negative electrons
Describe how you can give an object a positive charge
To give an object a positive charge , remove the electrons
Describe how you can give an object a negative charge
To give an object a negative charge, add electrons
What types of objects repel
Objects which have the same charge repel
What types of objects attract
Objects which have opposite charges attract
What does a neutral object have
A neutral object has an equal number of negatively charged electrons and positively charged protons.
Explain how the balloon sticks on the wall
The negative electrons in the wall are repelled by the negative charge on the balloon
The surface of the wall is therefore left with a positive charge
Positive and negative charges attract which causes the balloon to stick to the wall.
What will a charged object do
A charged object will produce an electric field around itself
What happens to any object inside an electric field
Any object in an electric field will experience a force
What does the size/strength of the electric field depend on
The size of the field depends upon:
1. The charge on the object creating the field
2. The distance from the object creating the field
Draw electric fields for positively charged objects and negatively charged objects
https://cdn.savemyexams.co.uk/cdn-cgi/image/f=auto,width=1920,w=1920/uploads/2022/12/electric-fields-igcse-and-gcse-physics-revision-notes.png
In what direction do the electric field lines go
At what angle are they to the surface
Electric field lines go from positive to negative
They are always at right angles to the surface
The _____ together the lines are, the ______ the electric field is
The closer together the lines are, the stronger the electric field is
What type of force do electric fields produce
The force produce by an electric field are an example of a non-contact force.
State the charge on an electron
The charge on an electron = -1.6 x 10 ^-19 C
State the charge on a proton
The charge on a proton = +1.6 x 10^-19 C
Explain how an object can become discharged (lose it’s charge)
If the charge on an object becomes sufficiently large, the electric field it produces will cause a spark to be produced, this will cause the object to lose its charge.
Explain how rubbing caused the balloon to become negatively charged
Electrons (which have a negative charge) are transferred from the jumper to the balloon, by friction
The balloon has more negative charge than positive therefore the balloon is negatively charged
Explain why the balloon moved away from the ruler
The balloon is negatively charged
Charges which are both negative repel
Explain why the balloon was hung from a nylon thread and not from a thin metal wire
The nylon thread is an insulator therefore the charge cannot be transferred away from the balloon
The metal wire is a conductor and will cause the charge to leave the balloon
What is the easiest way to discharge an object
The easiest way to discharge an object is to connect it to the ground with a metal wire.
This is called grounding or earthing.
How are sparks caused
Sparks are caused when there is a high enough potential difference between a charged object and the earth (or an earthed object)
explain how the presence of a strong electric field can cause a spark
Sparks are caused when there is a high enough potential difference between a charged object and the earth (or an earthed object)
A high potential difference causes a strong electric field between the charged object and the earthed object
The strong electric field causes electrons in the air to be removed (known as ionisation)
This makes the air conductive and allows current to flow to the earth in the form of a spark
Explain how refuelling an aircraft could become a problem in terms of static electricity
Electrostatic charge can build up as the fuel flows through the refuelling pipe
This could cause a spark and trigger an explosion
To prevent that, both the refuelling truck and the aeroplane are earthed
This prevents any charges from building up and leading to a spark
The person could receive a fatal electric shock if the kite was very close to, but not
touching the power cable.
Explain why.
2 electric field strength is very high
causing the air to become
ionised
(the kite / string) conducts
charge to the person / earth
A negatively charged rod is held near an earthed conductor.
Explain why a spark jumps between the negatively charged rod and the earthed
conductor.
the (large) potential difference between the two objects
(causes negative) electrons
charges to move (through the air)
(from the rod) to the conductor
