sem-II revision-chapter8

SEM II - REVISION-CH8

An Insulator can be charged by friction (rubbing)

glass rod - silk

plastic or ebonite - fur

STATIC ELECTRICITY

• Plastic pen rubbed with silk - electrons transfer from wool to plastic. The plastic pen becomes negative and wool becomes positive.

• Like charges repel and unlike charges attract each other.

• Friction can produce a charged body.

• When two charged glass rods are brought together, they repel each other.

• When a charged glass rod is brought near a charged ebonite rod, they attract each other.

• The negative charge means excess of electrons.

• The positive charge means less number of electrons.

ATOM

An atom consists of electrons, protons and neutrons.

Electrons are negatively charged.

Protons are positively charged.

Neutrons have no charge.

The number of electrons is equal to the number of protons.

The electrons revolve around the nucleus in a definite orbit. Electrons far away from the nucleus are free to move out of the orbit.

Multiple Choice

An ebonite rod rubbed with fur, charge developed on the ebonit rod is ____________.

• Positive

• Negative

• Neutral

• Both

Multiple Choice

The number of electrons and protons in an atom is ________.

• unequal.

• unknown.

• the same.

• different.

Multiple Choice

A conductor has a large number of ____________.

• protons.

• charges.

• atoms.

• free electrons.

Multiple Choice

Mercury is ______________ of electricity , while pure water is _____________ of electricity.

• an insulator, an insulator

• a conductor, an insulator

• an insulator, a conductor

• a conductor, a conductor

Multiple Choice

Charges are shared between the conductors during the method of ____________

• Conduction.

• Induction.

• Charging

• Rubbing.

Multiple Choice

Charging a body without touching is called ________.

• Conduction.

• Electroscope.

• Charging by friction.

• Induction.

Multiple Choice

The factor responsible for charging is:

• transfer of electrons.

• transfer of protons.

• transfer of neutrons.

• transfer of protons and electrons.

Multiple Choice

A glass rod rubbed with silk is touched with a negatively charged electroscope. The divergence of the leaves will ________.

• increase.

• decrease.

• remain the same.

• first decrease and then increase.

Multiple Choice

The rod in an electroscope is made up of ________.

• Gold

• Brass

• Copper

• Aluminium

Multiple Choice

When a charged cloud passes over the earth, it acquires a charge by induction.The spark which occurs is called __________

• thunder

• lightning

• lightning conductor

• static electricity

Multiple Choice

which one is not safe during lightning?

• Do not stand under a tall structure.

• Travelling in a closed vehicle.

• Lie on the ground.

• Switch off all the electrical appliances.

Multiple Choice

A device to protect the tall buildings from getting damaged during lightning.

• Lightning conductors.

• conductors.

• Insulators or conductors.

• Lightning rods.