Grade 9 physics

Atoms contain what charges

Protons (positive) and electrons (negative)

What causes electricity?

Movement of electrons

Do protons move?

No — protons DO NOT move

Which particles move in static electricity?

Electrons

What are conductors?

Materials where electrons move easily

What are insulators?

Materials where electrons do NOT move easily

Give examples of conductors

Metals (copper, iron), water with ions

Give examples of insulators

Plastic, wool, glass, dry wood

Equal protons and electrons = ?

Neutral charge

Gains electrons = ?

Negative charge

Loses electrons = ?

Positive charge

Like charges do what?

Repel

Opposite charges do what?

Attract

Why do neutral objects attract charged objects?

Charge separation occurs

What is charge separation?

Electrons shift inside a neutral object

What happens after charge separation?

Opposite charges attract

Static electricity is caused by?

Electrons being added or removed

When electrons move, an object becomes?

Charged

Three methods of charging

Friction, Conduction, Induction

Which methods require contact?

Friction and conduction

What is charging by friction?

Rubbing two neutral objects together transfers electrons

Result of friction?

One object becomes negative, the other positive

What determines who gains electrons?

Electrostatic series

What is conduction?

Charging by contact

Electrons move from?

More negative → less negative object

After contact, objects have what charge?

Same type of charge

Negative rod touches neutral object → result?

Object becomes negative

Positive rod touches neutral object → result?

Object becomes positive

What is an electroscope?

Device that detects charge

What is induction?

Charging without contact

Two types of induction

Temporary and permanent

Temp induction: Negative object near neutral → electrons do what?

Move away

Temporary induction: Positive object near neutral → electrons do what?

Move toward it

Temporary induction: What happens when object is removed?

Charges return to normal

What is grounding?

Connecting to Earth to remove charge

What does grounding do?

Neutralizes object

When does permanent induction occur?

When grounding is used

Final charge after induction + grounding?

What is discharge?

Loss of stored charge

Three ways to discharge

Grounding, contact, through air (lightning)

What is lightning?

Giant electrical discharge

negative

What is the bottom of a cloud charge

Ground becomes what charge?

Positive

Why do tall objects get struck?

Closest to charge

What is a lightning rod?

Metal rod that directs lightning safely to ground

Source of positive charge?

Protons

Source of negative charge?

Electrons

Which particles move?

Electrons only

Why do leaves of electroscope spread?

Same charges repel

What causes a spark?

Electrons moving through air

Why do sparks produce light?

Excited air particles emit light