Static Electricity

Question 1

Insulators are given a…

Answer 1

Static charge when rubbed with another insulator

Question 2

Law of Electrostatics:

Answer 2

Like charges repeals and opposite charges attract

Question 3

The greater the static charge stored…

Answer 3

The greater the potential difference between it and the earth

Question 4

If the potential difference becomes high eneough,…

Answer 4

A spark may jump across the gap

Question 5

The danger of electrostatic electricity and how to reduce the chance of sparks and explosions

Answer 5

Static electricity can cause sparks and often these sparks are small. When it happens an object has enough of these charges if can cause discharge causing the air to conducts and produce sparks

Question 6

The hazards from petrol tankers

Answer 6

• A static charge can build up on a petrol tank because of the tyres rubbing on the road (to produce static electricity - A static charge can also build up as petrol flows through the pipe (to produce static electricty)
• Therefore underground metal tanks are connected to the earth to prevent sparks
• Metal stripes are connected to the task before the tank is opened to prevent sparks
• As petrol is very flammable, even a very small spark can cause serious fire when petrol old petrol vapour is opened to the air
• At filling stations, petrol is transferred from tankers to underground tanks. There will therefore be
  No sparks will doing this.

Question 7

Why is earthing done?

Answer 7

• To earth something you must connect it to the earth with a conductor
  The conductor allows electrons to flow through it; this is called current electricity
• When there is a NEGATIVE charge, the conducting object is earthed, electrons move from the earth to the object
• Where there is a POSITIVE charge, the object is earthed, the electrons dove from the earth to the object

Question 8

A charged conductor can be discharged by …

Answer 8

Connecting it to the earth with a pipe.

Question 9

How does an object gain a negative charge by describing the motion of electrons?

Answer 9

When two objects rub, they transfer electrons. If an object losses electrons, there will be more protons than electrons, causing the object of be positively charged.

Question 10

How does an object get a negative charge by describing the motion of electrons?

Answer 10

When an object gains electrons, there will be more electrons that protons. Due to this imbalance, the object is negatively charge

Question 11

Describe how an object is given an induced charge when another charged object is brought close to it.

Answer 11

• The black powder having been charged by the gun is positively charged. This means it attracts objects near it
• Some of the paint will go back on the gun whilst some will go on the frame
• A fine even spray is produced as the positive electrons on the bike already repel away

Question 12

Explain why metals cannot stop a static charge, unless they are isolated.

Answer 12

Because as soon as there are too many electrons in one place, they repel each other and spread out, reducing or eliminating the effect.

Question 13

How is static electricity is useful for spray painting

Answer 13

• Saves time

- Paint entire surface as if spreads evenly across the bike

Question 14

Explain how an electrostatic precipitator works

Answer 14

• The dust and the wast gases rise up and reach the positively charged grid
• When passing the grid the dust becomes positively charged, the dust particles repel each other
• After passing the rid, they are surrounded by earthed plates
• As a result of the plated being surrounded by positively charged electrons they gain an induced negative charge
• This allows them to attract to one another
• The negatively charged plate electrons attract to the positively charged electrons
  The waste gases left, travel up.