# حل درس Electric Charge الفيزياء الصف العاشر

## حل درس Electric Charge الفيزياء الصف العاشر

Recap

1.Objects become electrically charged as a result of the  transfer of

• protons.
• √  electrons.
• neutrons.
• nuclei.

When a glass rod is rubbed with silk and becomes positively charged,

• √ a .electrons are removed from the rod.
• b .protons are removed from the silk.
• c. protons are added to the silk.
• d .the silk remains neutral.

What happens when a rubber rod is rubbed with a piece of fur, giving it a negative charge?

• a .Protons are removed from the rod.
• √ b .Electrons are added to the rod
• c .Electrons are added to the fur.
• d.The fur is left neutral.

1. The nucleus of an atom has a _______________ electric charge.
• √ a .positive
• b .negative
• c .neutral

Learning Objectives

• Demonstrate that charged objects exert force, both attractive and repulsive.
• Charging is the separation, not creation of electric charge. (Conservation of charge)
• Differentiate electrical conductors and insulators.
• Explain why metals are good conductor of electric charge.

Keywords

Electrostatics

Static Electricity

Charge

Electrostatic Force

Neutral

Gravitational Force

Conductor

Insulator

Metals

Why does the sticky tape get stuck to his hand?

Why does the sticky tapes repel each other in the second demonstration?

Why does the sticky tapes attract in the third demonstration?

LO: Demonstrate that charged objects exert force, both attractive and repulsive.

Which object gains and which object loses electrons?

Materials have varying ability to acquire charge.
Rubber and plastic have tendency to become  negatively charged. Glass and wool have tendency to become positively charged.

Triboelectric series –
The triboelectric series is a
list that ranks materials
according to their tendency to gain or lose electrons.

Summary- Properties of electric charges

1. There are two kinds of electric charges –

positive and negative

• like charges repel
• unlike charges attract
• Charged objects attract neutral objects
1. Electric charge is conserved.

No charge is created or destroyed.  It is only transferred from one object to the other.

Concept Check

3. Upon entering the room, you observe two balloons suspended from the ceiling. You notice that instead of hanging straight down vertically, the balloons seems to be repelling each other. You can conclusively say…
a. both balloons have a negative charge.
b. both balloons have a positive charge.
c. one balloon is charge positively and the other negatively.
d. both balloons are charged with the same type of charge.

Which Objects Will Conduct Electricity?

PhET Sims Science / Math
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Metals As Good Electrical Conductors

Explanation:

1. The metallic structure of metals typically have electrons that are only weakly attracted to their atoms.
2. These electrons can be freed and move easily between atoms and flow through the metal.
3. The atoms are now called ions because they do not have the same number of electrons as protons

Air Insulator Or Conductor?

Typically air is an electrical insulator

If there is a great enough difference in charge then electrons are forced towards the positive charge even moving through air, plasma is formed in the air which conducts electricity (this is lightning).

plasma (consists of negative electrons and positive ions)

Summary

Electrical conductors allow electrons to flow freely through them.

Electrical Insulators do not allow electrons to flow through them.

Metals are good conductors because they have free electrons to move freely.

Air and Carbon can be a conductor or an insulator depending on the situation.

Plenary

1.Which of the following materials would be relatively good conduct electricity? (can select more than one answer)

1. a) rubber b) aluminum   c) silver   d) plastic   e) wet skin

1. An electrical conductor is different to an insulator because a conductor ________________________.
• a)has an excess of protons
• b)can become charged and an insulator cannot
• c)does not have any neutrons to get in the way of electron flow
• d)None of the above answers are correct
1. What material would be safest to use as an insulator to cover electrical wires and why?

a) Aluminum b)Tin    c)Rubber   d)Water

Answer : C because rubber is a good insulator so it will not conduct electricity and keep the wire safe from someone getting an electrical shock if they touch it.

2. Charged Objects After you rub a comb on a wool sweater, you can use the comb to pick up small pieces of paper. Why does the comb lose this ability after a few minutes?
3. Types of Charge A pith ball is a small sphere made of a light material, such as plastic foam, that is often coated- with a layer of graphite or aluminum paint. How could you determine whether a pith ball suspended from an insulating thread is neutral, charged positively, or charged negatively?

2. The comb loses its negative charge to its surroundings and becomes neutral once again.
3. Bring an object of known charge, such as a negatively charged hard rubber rod, near the pith ball. If the pith ball is repelled, it has the same charge as the rod. If it is attracted, it may have the opposite charge or be neutral. To find out which, bring a positively charged glass rod near the pith ball. If they repel, the pith ball is positive; if they attract, the pith ball must be neutral.

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