Electric sparks:
1: why do clouds become charged? Because they contains tiny crystals of ice which are constantly moving and rubbing on each other.
2- What is a flash of lightning? When is a lightning produced? Is an avalanche of electrons?
It´s produced when a thundercloud can become so highly charged that huge numbers of electrons jump the gap between a cloud and earth.
3- What special precautions are taken in factories using flammable materials? Why are these precautions taken? The workers have to wear special shoes and clothes which don´t build up charges. Because even the smallest spark can produce an explosion.
4- Have you ever produced sparks? If so, explain what happened. Yes I did, when I was near to the TV and it give me a little bit of charge and then I touch another person because we have different charges so it produces a little sparks.
5- Airplanes become charged up when they fly through clouds. Explain why.
´cause they have to cross the clouds so the airplane takes the charge of the clouds and they don´t have any form to throw the energy to the earth, so when it arrive it throw the energy to the earth.
6- What causes a clap of thunder? The energy of the clouds and the energy of the earth found each other and when it happened it produce sound.
- Why tall buildings have lightning conductors?
- Cause is more probable that a spark fall in the tall buildings so they need a conductor to can throw all the energy that can fall in the building and throw it to the earth

Electric circuits:
An electric circuit is a path along which electricity can flow. To make up a circuit you need a battery, a bulb and two wires. The wires and used to join the battery to the bulb. The batteries job is to push an electric current trough the wires and the bulb. The bulb lights up as the current flows I through it.
Meters and switches:
If you want to measure the size of the current, you have to put a meter into the circuit. Current is measure in amperes (A) or amps for short.
The meter for measuring current is called an ammeter.
If you want to turn the bulb on and off easily you should use a switch. A switch works by opening and closing a gap in the circuit. When the switch is turned off, a gap opens up. This stops the flow of current all round the circuit.
When the switch is turned on, the gap is closed this makes a complete circuit and the current can flow.

Currents.
In a series circuit the same current flows through each part of the circuit. There is only one path for the current to flow round. Circuits A and Bare series circuits.
In a parallel circuit the current divides when ir comes to a junction. Part of the currents flows through the other branch. Part of it flows through the other. The bulbs in circuit C and D are joined in parallel.
When two branches have the same resistance, the same current flows through each branch

Conductor and insulators.

Conductors: a substance which allows electricity to flow through it, f. ex copper are used to carry current, electric current is carried round your home by copper wires.
Iron silver, tin, aluminum, gold, mercury and carbon are conductors
Insulators: a substance which does not allow electricity to flow through it. Insulators are used for safety. The electricity used in your home can be dangerous. You could easily be killed if you touched a bare wire. That is why plugs and wires are covered with insulators like: rubber, plastic, wood, wool, paper, glass, sting, nylon etc…..

Making the right connectors.
The quiz board
The railway signal
When a battery is working, the energy change is:
Chemical energy---- to electrical energy.
The battery´s chemical energy is used up pushing a current round the circuit. The ´´electrical push´´ which the battery gives to the current is called the voltage. It is measured in different volts (v) on a volt-meter.
Different batteries produce different voltages. The bigger voltage supplied by the battery the bigger will be the current that flows in a circuit.

Electricity.
Is a kind of energy. It has two different kinds of charge: positive charge and negative charge.
+ And +: repel.
-And +: repel.
+and -: attract.
Before rubbing, the pen has equal numbers of positive and negative charges. The changes when the pen is electrically neutral.
When the pen is rubbed with other thing, negative charges travel from the other thing to the pen. The pen now has more negative charges than positive charges. It has become negatively charged, because the negative charges have left the other thing, it now has more positive charges than negative, it has become positively charged.
Atoms contain negatively charged particles: electrons.
Positively charged particles: protons.
Neutral particles: neutrons.

Genes.
Whether you are naturally tall or small, blond or brown haired, blue or green eyed, left or right handed; depends largely on the genes in your body cells.
A gene is a part of one of the chromosome threads inside the nucleus of each cell, those control the characteristics which are passed on from parents o their children.
When an egg is fertilized two sets of genes are put together, one set comes from the father in the sperms chromosomes and the other set from the mother in the egg´s chromosomes. Each carries half of the total instructions for the new human. Those genes passed carry instructions about body characteristics like height, hair color and eye color.
Dominant genes: the genes with ´´stronger ´´ or dominant instructions will control happens.
Heredity: is the passing on of characteristics from one generation to the next.
Chromosomes: are fine threads of material for carry instructions. There are 10.000 genes on each chromosome.
Human cells have 46 chromosomes. Sperm and eggs have only half that number. When a sperm and eggs join a new being begins to grow.


The three man stages of cells division.
First stage: Each chromosome makes an exact copy of itself.
The copies separate one chromosome from each pair goes to opposite sides of the cell.
Third stage: The cell divides. New nuclei form. Each daughter cell has the same chromosomes as the parent.

Baby: the first nine months.
WE used to thinking of a baby being age 0 on the day it is born. But it has been growing for about nine months before it enters the world. This is what happens in the nine month (38 weeks) before is born.
Week 0--- egg is fertilized in the tube.
Week 1---- Embryo becomes attached to the womb.
Week 2----Embryo´s eyes being to develop. Its legs and arms are tiny bumps.
Week 6----Embryo begins to look like a human. Ears, hands and feet begin to grow, heart begins to beat.
Week 10---Baby´s finger and toes grown .It can move its arms and legs a little, it can even swallow.
Week 14---If doctors could see the baby, they could tell if it was boy or a girl.
Week 18---Baby has hair .eyebrows. Doctors can hear its heart beat. It can move…mother begins to feel its kicks.
Week 26---Baby opens its eyes.
Week 30--- If born now, the baby could live with special care.
Week 34---Bay has grown a lot of fat in the last four weeks, to keep it warm when it is born.
Week 38---Baby is born.