Physics Chapter 15

What does an atom consist of?

It consists of electrons orbiting a nucleus made up of neutrons and protons

An electron has a negative charge, while a proton has a …

positive charge

What is the SI unit of electric charge?

coulumb(C)

Each electron has the same amount of charge as a proton. (T/F)

True

What is the charge of a proton?

1.6 × 10^-19

An atom contains an equal number of protons and neutrons. (T/F)

True, which is why an atom is neutral

When an atom gains one or more electrons, …

it becomes a negatively charged particle

When an atom loses one or more electrons, …

it becomes a positively charged particle

Like charges …

repel each other

Unlike charges …

attract each other

What is an electric field?

An electric field is a region in which an electric charge experiences an electric force

What is an electric force?

A force exerted by an electric charge on another nearby charge

The electric force is only attractive. (T/F)

False, the electric force can be both attractive or repulsive

How do we know the nature of electric fields?

We can do that with the help of test charges

The electric field for any arrangement of charges can be represented using electric field lines according to certain guidlines like?

The arrows must always point towards a negative charge and away from a positive charge

The lines are closer together when the electric field and electric force are stronger

The field lines never cross one another

What are the 2 ways to electrostatically charge an object?

Through induction or friction

Atoms of different elements have different characteristics due to their …

different compositions

The electrons of some atoms are held more strongly by their nuclei than the electrons in other atoms. (T/F)

True

When 2 objects like hair and a balloon come into contact, …

the less tightly held electrons from hair are attracted and transferred to the balloon. The oppositely charged hair and balloon attract each other and thus stick together

Static electricity is only caused when the objects in contact are both insulators. (T/F)

True

Rank some materials for electrostatic charging, from greater comparative tendency to lose electron to greater comparative tendency to gain electron.

Air, leather, glass, human hair, nylon, wool, silk, polyester, vinyl, silicon rubber, ebonite

Can positive charges move?

No, they can never move as they are protons and a change in protons would mean a change in atoms

What does induction involve?

Induction involved placing a charged rod close to the conductors without contact. This induces the redistribution of charges in the conductors.

What are the steps to charge one conductor?

1. Place a charged rod close to the conducting spehere. The unlike charges accumulate on the side nearer to the charged rod while the like charges accumulate on the other side

2. Touching the sphere on the right allows the electrons to be repelled further away into the person’s body

3. Remove the hand from the sphere

4. Remove the charging rod

What is an alternative to touching the sphere in step 2?

It is to connect one end of a metal wire to a metal water tap and use the other end to touch the sphere, allowing the electrons to flow to the Earth through the pipes. This is called earthing

What are the steps to charging 2 conductors?

1. Place a charged rod close to one side of the conducting spheres that are in contact. Positive charges in the rod attract free electrons to the left, leaving the right side positively charged

2. Keeping the rod in position, separate the 2 spheres to isolate the 2 groups of opposite charges

3. Remove the charged rod. The 2 spheres now have equal but opposite charges