المراجعة النهائية علوم الصف الخامس الابتدائى (الكهربية والمغناطيسية ) علوم لغات

Magnetism
* The Ancient Greeks discovered a type of rocks located in an area named magnesia.
* The discovered rock has Natural force to attract the materials made of iron.
* They named the force magnetism and the black rock is called
Natural Magnet.
Natural Magnet: One of the iron ores which is known as magnetite Different shapes of magnet.
Bar magnet - horse shoe magnet - Round magnet - Needle magnet.
Kind of Materials:
1. Magnetic substances
2. Non-magnetic substances
Materials that attract to magnet.
Ex: Iron-Cobalt-Nickle-Steel.
Materials that don't attract to magnet.
Ex: Alaminium-Copper-Glass-Chalk
Properties of magnet:
Magnetic field.
The area around magnet from all directions is called magnetic field.
* each magnet has two poles.
Poles of magnets:
The Area - at the two ends of the magnet which attracts a greater number of paper clips.
* Direction of the free motion magnet.
* When a magnet is freely hold one of its poles direct to North direction which is called North Pole of magnet and the other pole direct to the South Pole and it is called South Pole of magnet.
- Like poles repel each other.
Dislike poles attract each other.
South + south --> repel.
North + north --> repel.
North + south --> attract
Magnetic field:
The space around magnet in which the effect of magnetic force appears through.
Magnetic force:
The ability of magnet to attract the magnetic materials existed in its field.
Compass:
Instrument used to identify the four geographic directions.
Idea of compass depends on the magnetized Needle that can spin freely to determine North and South Poles.
Q1- Complete the following:
1- The Natural magnet is .......... stone named .......... .
2. The Natural manget was discovered in .......... area.
3. The magent takes many shapes as .......... and .......... .
4. From magnetic substance is .......... while .......... is from non magnetic substances.
The area around magnet in which its ability appear is called ..........
6. The magnet has .......... poles.
7. Like poles .......... while unlike poles .......... .
8. We can determine geographic directions by .......... .
Q2- Mention an example for:
1. One shape of magnets.
2. Magnetic substance.
3. Non-magnetic substance.
4. Instrument to determine geographic directions.
Q3- Compare between:
1- Magnetic - Non-magnetic substances
Magnetic: Substances that attract to magnet.
Ex. Iron. Cobalt.
Non-magnetic substance: Substance don't attract to magnet.
Ex. Copper-Gold.
2- Natural magnet - man made magnet
Natural magnet:
Blacks stone
Named magnetic
man made magnet:
Takes many shapes
Bar - Round - horse shoe
Q4- Give reasons for:
1. Using magnetic needle in compass.
Because it can spin freely to determine geographic directions.
2. Iron is magnetic substance.
Because it can be attracted to magnet.
3. Glass is Non-magnetic substance.
Because it dosen't attract to magnet.
Q5- What happens if:
1. North pole of magnet is closed to North pole of another
2. Hang a magnet freely.
Q6- Write the scientific term:
They will repel.
It will be directed to North pole of earth.
1. The strongest area in magnet at two ends.
2. The ability of magnet to attract things made of iron.
3. One of iron ore named magnetite.
4. Instrument used to determine geographic directions.
Magnetism and electricity
* The magnetic field can be generated by using an electric current.

* When an electric current passes through a wire it produces a magnetic field.
* How can we make an electromagnet?
When electric current passes through a twisted wire in the form of a coil around a wrought iron bar. The wrought iron bar becomes a magnet and it is known as "the electromagnet".
Note:
* The magnetic force of electromagnet can be increased by increasing the number of coil turns or by increasing the intensity of electric current passing through the coil by using many batteries.
Uses of electromagnet:
1- In winch to move heavy Iron blocks.
2- Electric bell.
3- Electric Mixer.
4- Disc drive.
5- Television.
Generating electric current from magnet:
* The scientist Faraday discovered that on moving a wire between two poles of magnet an electric current is produced in the wire.
* Faraday uses this discovery to make electric generator [dynamo].
* The electric generator changes Mechanical energy [Kinetic] into electric energy.
* Dynamo is used in many objects.
1- In bicycle it contains a small cylinder that touches the bicycle wheel tire-and it is connected to U-shaped magnet.
2- In electric power stations they use a huge electric generators that contain many great coils that turn between two poles of a huge magnet used for lightening cities.
How can we increase a mount of electricity from Dynamo?
1- Using a strong magnet.
2- Increasing the number of turns in the moving coils.
Q1- Correct the words between brekets:
1. The magnetic field can be generated by (water) current.
2. The (Natural Magent) is used in winch.
3. (Motor) can be used to generate electricity.
4. Electric generator in bicycle used (Huge) magnet
Q2- Complete the following:
1. The electric generator changes ......... energy to ......... energy.
2. Power stations depend on ......... to generate electricity.
3. The electric current has ......... effect on passing in wires.
4. Electromagnet can be used in ......... .
5. The scientist ......... discovered the idea of electric generator.
6. The best iron used in electromagnet is ......... iron.
. The Dynamo in bicycle uses ......... magnet.
8. When electric wire moves between poles of magnet ......... is generated.
Q3- Give reasons for:
1. The electric current has a magnetic effect.
Because when it passes inside wires, it produces magnetic field.
2. Electromagnet has many uses.
Because it can be used in winch-electric bell and mixer.
3. Power stations use huge magnets.
Because it produces energy to lightining cities.
4. The magnetic force increases by increase number of battery.
Because the electric current intensity will increase.
Q4- What happens when:
1. A bar of wrought iron surrounded by wire contains electric current.
It will be electromagnet.
2. A wire moves between-two poles of magnet.
It will produce electric current.
Q5- Write an example for:
1. An instrument depends on electromagnet.
electric bell
2. An instrument used to move heavy blocks of iron.
3. An instrument used to generate electricity.
1 - The Natural magnet has ............... colour.
Black blue white red
2 - The coloured object seen by its colour through ...
Transparentopaquedarkshadow
3 - Magnet takes many shapes.
True False
4 - The darkned Area behind opaque body is ...........
Light shadow photopicture
5 - The change in light speed causes ...............
refraction
reflection
difuse
deflection
6 - The separation of light done by ...............
prism
glass
mirror
tissue
7 - Geographic directions can be determined by compass
True
False
8 - The main source of light on earth is .............
sun
lamp
moon
candle
9 - The strongest points in magnet in the ............
ends
middle
around
before

10 - Cobalt is non-magnetic substance.
True
False
11 - From primary colours ...............
red
cyan
magneta
yellow
12 - Natural magnet has black color.
True
False
13 - On mixing two primary colors we get secondary colo
14 - Shadow is formed from opaque bodies.
True
False
True
False
15 - From magnetic substances ...............
iron
copper
glass
plastic
16 - Unlike poles attract.
True
False
17 - The instrument that changes mechanical energy to e
Dynamo
motor
electric mixer
compass
18 - Moon produces light by itself.
True
False
19 - From secondary colours ...............
cyan
red
blue
green
20 - Geographic directions can be determined by .......
compass
Dynamo