1、It is a dry winter day. You shuffle across a carpet and touch a doorknob. Zap! You get an electrical shock.When you walk across a carpet, electrical charges from the carpet build up on your body. You receive a small shock from the discharge of static electricity. 似乎是带电离子的聚积Water droplets in the clou
2、ds bump and rub against one another.Suddenly, negative charges streak down to the positively charged ground.If you are far from any shelter, then go to the lowest point and crouch down. Lightning often hits the tallest object in an area蹲伏下来Conductors are materials that let flow through them easily.I
3、nsulators are materials that do not let charges flow through them easily.SemiconductorElectrical charges can also be made to flow continuously through materials.You flip a switch on the wall, and the room lights up.When you plug a device into an outlet, the device becomes a part of a circuit.A simpl
4、e circuit has three basic parts. It has a power source, such as a battery. This powers a load, such as a lamp or a computer. Connectors, such as wires, carry electrical charges between the power source and the load.Many circuits have a switch.A complete, unbroken circuit is called a closed circuit.
5、If the circuit has any breaks or openings, it is called an open circuit.When a light bulb burns out, it makes an open circuit. The parts of a series circuit are connected in one loop. The electric current moves along one path.A parallel circuit is a circuit in which the electric current flows throug
6、h more than one path.These different paths are often called branches.If a light bulb on one branch burns out, the light bulbs on other branches will still glow.Most wall outlets, which get power from a power plant, have 120 volts.Resistance is the ability of a substance to oppose or slow down electr
7、ic current.A path with almost no resistance is sometimes called a short circuit.Some furnaces use electrical energy to heat homes. 火炉，暖气炉An incandescent (inkuhnDESuhnt) bulb produces heat and light. Inside an incandescent bulb is a thin wire called a filament. As thefilament resists electric current
8、, it heats up and glows.白炽灯A fluorescent (flawRESuhnt) bulb uses a gas toproduce light.荧光灯Transformers are used to change the voltage of electric current.估计是变压器A step-up transformer is used to boost the voltage. Step-down transformers change the voltage of electric current so it can be used in your
9、home.At a higher voltage, more current can flow through a cable.Electrical cable 是电线吧？A circuit breaker stops the flow of charges by switching off the current if it gets too high. 闸刀吧A fuse melts if the electric current in the circuit gets too high.钨丝一类的，不知道怎么称呼Electrical power is measured in units
10、called watts.First, slide a slice of bread into each slot in the top of the toaster. 狭缝；投币口Next, push down the lever on the side of the toaster. LeverageThe bread slices should drop down inside. Inside the toaster, electric current causes wire coils to heat up and toast the bread.电线圈When the bread i
11、s toasted, the slices pop up from the slots. Spread butter or jam over the toast and enjoy.Hybrid is a word that describes something that is a mix of two different things. Hybrid cars use two different power sources: gasoline fuel and electrical energy.You may have played with magnets and watched th
12、em snap together or push apart.The force that pushes magnets apart or pulls them together is called magnetic force. The parts of a magnet where the magnetic force is strongest are called the magnetic poles .Magnetite is a natural permanent magnet containing iron.iron, nickel, and cobalt 应该是铁，镍，钴The
13、aurora australis is a display of lights near the South Pole.Charged particles from the Sun become caught in Earths magnetic field and give off light.Ancient sailors used compasses to navigate the seas when they could not see land or stars.You can also make the magnetic field stronger by winding the
14、wire into a long coil. Each loop of wire is like a little magnet that has its own magnetic force.An electromagnet is a coil of wire wrapped around a metal core, such as an iron bar.The diaphragm (DIGHuhfram) is the part of the loudspeaker that vibrates to create sound.A microphone is a device that u
15、ses a magnet to convert sound into electrical signals. When you speak into the mouthpiece, a diaphragm vibrates.An electric motor is a device that changes electrical energy into mechanical energy (muhKANikuhl ENurgee), or motion. Electric motors power tools, toys, and other machines.A simple electri
16、c motor has a power source, a permanent magnet, a rotating loop of wire, and a motor shaft. The shaft is a rod that can spin and move.An electric generator turns motion into electrical energy. The opposite of a motor, it changes mechanical energy into electrical energy.Fossil FuelsOil, coal, and nat
17、ural gas can be burned to heat water, producing steam.The mechanical energy for a generator is provided by a turbine.A simple turbine looks like an electric fan.应该是类似于风力发电器那样的，利用机械能转化电能的螺旋部件Alternating current (AC) flows in one direction and then flows in the opposite direction.When the flow of a cu
18、rrent is always in one direction, it is called a direct current (DC).A battery is an example of a DC power source.a horseshoe magnetNow suppose you are a bird. Winter is on the way.Its time to migrate south. But you hatched just this summer.Have you ever experienced a blackout? This is when electric
19、 current stops flowing to your home. When this happens, electricians are the ones who fix the problem. They install and repair electrical alarms, switches, wiringyou name it! Suppose that you are building a new stadium. The lights, retractable roof, and scoreboard all run on electrical energy.So doe
20、s the heating, cooling, and security systems. All of these features are designed by an electrical engineer. Electrical engineers plan and construct all kinds of electrical systems.G4 完结G5，G6 生词过多，直接看，不再有截取笔记；跳到 science readerThis sheep lives in a rocky place. It has hooves to help it climb.Popsicles can melt. 冰棍During winter some plants and insects are dormant. They are inactive.Some animals hibernate in winter. They are resting to save energy.hibernate ，to pass the winter in a state of rest
