SP11

Question 1

Why does an insulator not conduct electricity

Answer 1

The electrons are fixed so cannot flow

Question 2

How is an insulator charged by friction

Answer 2

When two insulators are rubbed together it can be charged electrons are transferred from one object to another

This causes one insulator to be positively charged and the other to be negatively charged

Question 3

Why does an insulator become positively or negatively charged

Answer 3

A positive static charge forms on the insulator that loses electrons

A negative static charge forms on the insulator that gains electrons

Which insulator loses/gains electrons is based on materials

Question 4

Why can conductors conduct electricity

Answer 4

Their electrons can flow as they aren’t fixed because they are delocalised

Question 5

What happens when conductors experience friction

Answer 5

If conductors are rubbed against each other, electrons will flow in/out and will cancel each other out keeping the conductors neutral

Question 6

Like charges

Answer 6

repel

Question 7

Opposite charges

Answer 7

attract

Question 8

What are sparks

Answer 8

The spark is when the charge jumps through the air from the highly negative charge to a highly positively charged object, to balance out the charges

Question 9

What is sparking

Answer 9

Sparking occurs when charge builds up and the objects are close but not touching

Question 10

What is lightning

Answer 10

Lightning is caused when the charge between the clouds and the earth is so great that a massive spark jumps across the gap to balance the charge

Question 11

What is an electro-static force

Answer 11

It is the force experienced by charged objects of either attraction or repulsion

Question 12

How is charge related to the strength of electro-static forces

Answer 12

The greater the charge the greater the force (Positive/Negative)

The closer the charges the greater the force as the force is proportional to the inverse square law

As objects are not touching it is a non-contact force

Question 13

How do charges relate to induction

Answer 13

A positively charged balloon next to the wall attracts the electrons in the wall as they are oppositely charged.

This induction causes the balloon to stick to the wall

A charged comb is able to pick up pieces of paper as it induces the opposite charge.

Question 14

What is earthing

Answer 14

It is the removal of excess charge by providing a low resistance pathway for electrons to flow through

Question 15

What does earthing accomplish

Answer 15

It allows materials to have a neutral charge

Question 16

What are the applications of electro-static charges in everyday life

Answer 16

Insecticides are given a charge and sprayed

This charge causes them to repel each other and are spread evenly and are attracted to the earth

If they are not given a charge then some droplets will blow away or they will all spread unevenly

Question 17

What are the dangers of sparking

Answer 17

If charge builds up and sparks while fuelling a car then an explosion can happen.

As fuel passes through a hose to the vehicle, a static charge can build up and when the charge is too big it can spark igniting the fuel

Hoses are earthed to avoid this

Question 18

What is an electric field

Answer 18

A region in which a charge will experience a non-contact, electric force.

All charged objects have an electric field and this field is stronger the closer you are to it

They point in the direction a positive charge would go which means towards negatively charged objects

They point to charges at right angles to the surface

Question 19

What are electric field lines

Answer 19

Lines representing an electric field, that point in the direction in which a positive charge would experience a force. The closer they are the stronger the field

Question 20

What is a parallel plate

Answer 20

The electric field between two charged plates is uniform. The field lines are parallel, equally spaced and point from the positive plate to the negative plate