What are the two types of electric charge?

Hot and cold Positive and negative North and south Strong and weak

Which rule correctly describes the force between electric charges?

Like charges attract; opposite charges repel All charges attract each other Like charges repel; opposite charges attract Charges only interact if they are touching

An atom normally has equal numbers of protons and electrons. What happens if an electron is removed from an atom?

The atom becomes neutral because the charges balance out The atom gains negative charge because fewer electrons means less shielding The atom becomes a positive ion — it has more protons than electrons The atom splits into two smaller atoms

You rub a balloon on your hair. The balloon becomes negatively charged. Why does it then stick to the wall?

Rubbing creates a glue-like substance on the balloon that sticks to walls The balloon becomes positive and the wall is always negative The negatively charged balloon repels electrons in the wall's surface, leaving a positive region that attracts the balloon Static electricity creates a magnetic force between the balloon and wall

The electric force between two charges follows an inverse-square law, just like gravity. If you halve the distance between two charges, what happens to the force?

The force halves The force doubles The force becomes four times stronger The force stays the same

What is an electric field?

The area inside a wire where electrons flow A region of space in which an electric charge experiences a force The voltage across a battery A type of magnetic field produced by static electricity

A Van de Graaff generator builds up a large positive charge on a metal sphere. A person touches the sphere and their hair stands on end. Why?

The generator creates a strong upward air current that lifts the hair Positive charge spreads to the hair; each strand becomes positively charged and repels the others Opposite charges in the hair are attracted upward toward the sphere The generator heats the hair, causing thermal expansion upward

How does lightning form?

Hot air in storm clouds rubs against cold air, creating friction that sparks Charge separation in storm clouds builds up until the electric field is strong enough to ionise air and create a conducting path to the ground Water in clouds conducts electricity that falls as lightning bolts The Sun's charged particles rain down on clouds, creating electrical discharges

Why is the electric force between a proton and electron in a hydrogen atom vastly stronger than the gravitational force between them?

They are equal — both forces follow the same inverse-square law Gravity is stronger at atomic scales because masses are tiny The electromagnetic force is about 10³⁹ times stronger than gravity at atomic scales They are different because electricity requires a medium but gravity does not

A lightning rod on a building is made of metal and connected by a thick wire to the ground. Why does this protect the building?

It repels lightning by generating an opposite electric charge It absorbs the lightning's energy and converts it to heat safely It provides a low-resistance conductive path for lightning to follow safely to the ground, bypassing the building It creates a Faraday cage that shields the building from electric fields