Introduction to Static Electricity

SNC 1PMr. M. Couturier

Electrical ChargeRecall from the chemistry unit that when

electrons are exchanged, ions are created. When the number of protons in an atom does not equal the number of electrons, we say that we have an electrical or electric charge. This will be the basis of electricity (note the root of the word in relation to electron).

Electrical Charge

Electrical ChargeWhen the imbalance of electrical charge is

such that there are more protons than electrons, then we say that the object is positively charged.

NOTE: Electricity is the exchange of electrons only. Protons are never exchanged in electricity.

Electrical Charge

Electrical ChargeWe therefore say that when there are more

electrons than protons, we have a negatively charged object.

Naturally, an object where the electrons equal the protons, is a neutral object.

Electrical ChargeNature is always seeking balance. It will

want to neutralize objects (recall ionic bonds which are electrically attractive but neutral when combined).

When objects rub against each other or collide, they exchange electrons in the direction of objects which desire their electrons against those that have trouble retaining their electrons.

Electrical ChargeObjects that have like charges repel each

other.Objects that have opposite charges attract

each other.This implies that an electric force will either

push apart two objects (repulsive force) or pull them together (attractive force).

Electrical ChargeNa and Cl form a very strong bond because

when the Na's electron is given to Cl, Na becomes positively charged while Cl becomes negatively charged. They then are electrically attracted to each by an electric force of attraction.

Electrical ChargeCharging objects by friction requires that

you understand the electrostatic series. See table.

Electrical Charge

Electrical ChargeReferring to your table, if human hair and a

rubber balloon are rubbed against each other, where do the electrons go?

Electrical ChargeSince the rubber balloon has a stronger

desire for the electrons, the electrons will travel from the human hair to the rubber balloon. Both objects are now charged! The human hair has an electrical imbalance such that there are more protons than electrons; hence the human hair is positively charged.

Electrical ChargeMeanwhile, since the electrons from the

human hair have moved to the rubber balloon, it is now negatively charged as it has more electrons than protons.

Electrical Charge