<p class="ql-block"><b>Electricity</b> </p><p class="ql-block">M: Electricity is a kind of energy, it plays an important role in our daily life, it makes our life more convenient. It is very dangerous. We can’t touch it. </p><p class="ql-block">In our country <span style="color: rgb(237, 35, 8);">power grid</span> provides us the electricity. Electricity flows into our house by wire. Everyone need to pay the bill of electricity every month. </p><p class="ql-block">Electricity has two charges: Negative charge/ positive charge. The same charges repel from each other, different charges pull together, Just like two poles in magnets. </p> <p class="ql-block">I will show you how electricity power our lamp </p><p class="ql-block">Electricity is stored in the battery. We connect the battery with the lamp by the wire. When we turn on the switch, the lamp is lit up by electricity. Electricity can flow in the wire, transfer the energy to light up the lamp. But what if I put a rubber box between the lamp and the battery. What will happen? The lamp can’t be lit up. Because the flow of electricity is blocked by the rubber box. None energy arrives at the lamp.</p><p class="ql-block"><span style="color: rgb(237, 35, 8);">Insulator</span>—Insulators stop the transfer of energy. They slow down the energy and make it difficult for it to pass through the object.</p><p class="ql-block"><span style="color: rgb(237, 35, 8);">Conductor</span>—Conductors help the transfer of energy . They allow energy to easily pas through the object</p> <p class="ql-block"><b>What is lightning</b></p><p class="ql-block">M: honey, have you seen a lightning? When can you see a lightning? Are you scared of it? </p><p class="ql-block">B: on stormy day.</p><p class="ql-block">M: Normally lightning can be seen on a stormy day. After the lightning, we can hear thunder roar loudly. Lightning is the most powerful electrical force on planet Earth. How does it form? Let me introduce it to you.</p><p class="ql-block"> </p> <p class="ql-block"><b>How does lightning form</b></p><p class="ql-block">Lightning begins as <span style="color: rgb(237, 35, 8);">static</span> charges inside a rain cloud. Winds inside the cloud are very strong. They lift water droplets from the bottom of the cloud to the top. Then the water droplets freeze. Meanwhile, other winds push ice down from the top of the cloud. Ice going down meets water coming up. When the ice meets the water, it pulls <span style="color: rgb(237, 35, 8);">electrons</span> off of the water droplets. It drags the extra electrons down with it.</p><p class="ql-block">The result is a cloud with two charges. The bottom of the cloud has a negative charge. The top of the cloud has a positive charge.These charges become very strong.</p><p class="ql-block">The gases in the middle of the cloud act as an insulator between these charges. An insulator is something that does not carry electricity. It traps the electrical charge inside the cloud.</p><p class="ql-block">Sometimes the charge becomes too strong, though. It <span style="color: rgb(237, 35, 8);">overpowers</span> the insulator. Electrons flow from bottom to the top of cloud. Then lightning happens.</p><p class="ql-block"><br></p><p class="ql-block">Lightning often happens between two clouds or inside a cloud. But Lightning can also travel from clouds to the ground, though.</p><p class="ql-block">Since the bottom of the storm cloud has a strong negative charge, it wants to flow toward a positive charge. The negative charge drops down like a ladder. It looks for a path toward the ground.</p><p class="ql-block">Meanwhile, positive charge particles also want to meet the negative charge. They "reach up" from the ground. When the two charges connect, lightning happens. The extra electrons in the cloud jump to the ground.</p><p class="ql-block"><br></p> <p class="ql-block"><b>What Causes Thunder</b></p><p class="ql-block">When lightning strikes, it heats up the air around it. The air can get hotter than the surface of the sun.</p><p class="ql-block">The heated air expands like an explosion. Then it shrinks back together. This makes the loud cracking sound of thunder. The air shakes in response. This causes the rumbling sound that follows that first loud crack.</p> <p class="ql-block"><b>Lightning and thunder </b></p><p class="ql-block">M: honey, have you notice every time we see the lightning first and then the thunder rumbles. Do you know why?</p><p class="ql-block">Light travels much faster than sound. Thunder and lightning start at the same time, but we will see the lightning first. On a race when a starting <span style="color: rgb(237, 35, 8);">pistol</span> is fired we see the smoke first and then hear the bang.</p> <p class="ql-block"><b>Lightning rod</b></p><p class="ql-block">Normally Thunder is very loud, It seems Much dangerous.In fact thunder won’t hurt you. But Lightning is different, it is very dangerous. Lightning can strike building, trees and people. Each year lots of people die from lightning strikes. It starts Forest fire. </p><p class="ql-block">What can help a building prevent striking from lightning? Lightning Rod!</p><p class="ql-block">A metal rod is attached to the highest part of the building. A conductor is connected from the metal rod to a metal plate in the ground. If the lightning strikes the rod, the conductor carries the negative charges into the ground.</p> <p class="ql-block"><b>Forest Fire</b></p><p class="ql-block">M: We know that lightning is electricity, it is kind of energy and can start a fire. There are three ingredients of making a fire—Fuel, oxygen and heat. </p><p class="ql-block">How a forest fire will be form? Is it in sunny day or rainy day? Sunny day is very hot, it makes things very dry. On a stormy day if the lightning strikes the trees, the trees catch a fire. The wind makes the fire move faster. A forest fire is formed. Sometimes without the lightning strikes, the sunny day lasts for a long time, the dry leaves and twigs may catch a fire by itself—self-ignition. Or volcano eruption cause a fire. These are natural causes of forest fire. </p><p class="ql-block"><br></p> <p class="ql-block"><b>Smoke and water vapor </b></p><p class="ql-block">Smoke and water vapor look like the same. Smoke comes from a fire, it is a cloud of tiny solid particles which is harmful for our lungs. Water vapor is a cloud of tiny water which is not harmful to humans. </p>