TOPIC 2 Electricity

Question 1

What are the types of charges that can move

Answer 1

The only charges that can be moved are negative electrons

Question 2

Describe how you can give an object a positive charge

Answer 2

To give an object a positive charge , remove the electrons

Question 3

Describe how you can give an object a negative charge

Answer 3

To give an object a negative charge, add electrons

Question 4

What types of objects repel

Answer 4

Objects which have the same charge repel

Question 5

What types of objects attract

Answer 5

Objects which have opposite charges attract

Question 6

What does a neutral object have

Answer 6

A neutral object has an equal number of negatively charged electrons and positively charged protons.

Question 7

Explain how the balloon sticks on the wall

Answer 7

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.

Question 8

What will a charged object do

Answer 8

A charged object will produce an electric field around itself

Question 9

What happens to any object inside an electric field

Answer 9

Any object in an electric field will experience a force

Question 10

What does the size/strength of the electric field depend on

Answer 10

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

Question 11

Draw electric fields for positively charged objects and negatively charged objects

Answer 11

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

Question 12

In what direction do the electric field lines go
At what angle are they to the surface

Answer 12

Electric field lines go from positive to negative
They are always at right angles to the surface

Question 13

The _____ together the lines are, the ______ the electric field is

Answer 13

The closer together the lines are, the stronger the electric field is

Question 14

What type of force do electric fields produce

Answer 14

The force produce by an electric field are an example of a non-contact force.

Question 15

State the charge on an electron

Answer 15

The charge on an electron = -1.6 x 10 ^-19 C

Question 16

State the charge on a proton

Answer 16

The charge on a proton = +1.6 x 10^-19 C

Question 17

Explain how an object can become discharged (lose it’s charge)

Answer 17

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.

Question 18

Explain how rubbing caused the balloon to become negatively charged

Answer 18

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

Question 19

Explain why the balloon moved away from the ruler

Answer 19

The balloon is negatively charged
Charges which are both negative repel

Question 20

Explain why the balloon was hung from a nylon thread and not from a thin metal wire

Answer 20

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

Question 21

What is the easiest way to discharge an object

Answer 21

The easiest way to discharge an object is to connect it to the ground with a metal wire.
This is called grounding or earthing.

Question 22

How are sparks caused

Answer 22

Sparks are caused when there is a high enough potential difference between a charged object and the earth (or an earthed object)

Question 23

explain how the presence of a strong electric field can cause a spark

Answer 23

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

Question 24

Explain how refuelling an aircraft could become a problem in terms of static electricity

Answer 24

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

Question 25

The person could receive a fatal electric shock if the kite was very close to, but not
touching the power cable.
Explain why.

Answer 25

2 electric field strength is very high

causing the air to become
ionised

(the kite / string) conducts
charge to the person / earth

Question 26

A negatively charged rod is held near an earthed conductor.
Explain why a spark jumps between the negatively charged rod and the earthed
conductor.

Answer 26

the (large) potential difference between the two objects

(causes negative) electrons
charges to move (through the air)

(from the rod) to the conductor