Alternative Energy Sources

In the future, we can assume our electrical needs will be just as great as they are now, and likely greater. However, this means we will have to be careful. Many of the sources of energy we use are non-renewable, meaning that we can't get more after we've used up what we have. One non-renewable energy source is fossil fuels. These are resources such as coal, oil, and natural gas. We are using these up quickly, and once they are done, there will be no more for thousands of years. Not only are they being used up quickly, their use contributes to global warming. We need to find alternative sources of power.

One possible source of power is nuclear energy. We can convert a tiny amount of nuclear mass into a lot of energy, and it does not pollute. However, nuclear power plants are expensive, the waste left over remains radioactive for thousands of years, and accidents can have huge impacts on the environment.

Another possibility is tidal power plants. These use the power from waves and water to generate electricity. The use of this sort of power is limited to coastal areas, but the earth's surface is mostly water, so we don't need to worry about running out any time soon. However, these types of power plants affect marine life and harm coastlines. Hydroelectric power, where the power of rivers is harnessed to produce electricity, is not limited to coastal areas and produces no pollution, but it requires an expensive dam to be built and interferes with fish migration.

Wind power is an option. Wind turbines are used in open areas and produce a lot of power. However, the wind doesn't blow every day. The power of the sun is also a possibility. Solar cells convert the sun's rays into electrical energy, but they are expensive and require direct sunlight.

While we figure out which power sources are best, we need to be more careful of our energy consumption. We won't have fossil fuels forever, and we need to take care of our environment.

Most circuits contain many loads. What happens when there is more than one resistor in a series, and they are parallel?

When resistors are arranged in a series circuit, the current passes through each resistor, down the line. In a parallel circuit, some power goes down either side of the circuit. A waterslide analogy can be used to explain the difference between an electrical circuit with two resistors in series and an electrical circuit with two resistors in parallel.

Each circuit consists of two slides. The electricity going through the circuit are the people going on the slides. One waterslide has the two slides connected, creating one long slide. The other has them separate, parallel to each other. People can choose to go down either slide. A person who slides down the longer slide will take longer going down, and fewer people will be able to go down the slide. On the parallel slides, more people will be able to go down.

Resistance

A resistor is part of a circuit that resists the flow of electrical current. It is the load in a circuit and converts the electrical energy to another form of energy. The unit of measurement for resistance is the ohm portrayed by the green letter for omega.

The amount of resistance offered by the resistor is determined by what it is made of, the size of the resistor, and the temperature. The resistance increases with length and decreases with diameter.

Ohm's law was determined in 1827 by Georg Simon Ohm. He discovered that the ratio of voltage to current was constant to a given conductor. The relationship can be written as an equation (above). R is resistance (in ohms). V is voltage. I is the current. All conductors resist electricity to a certain extent. Not all of them, however, obey Ohm's law. The resistance of a material depends on its temperature, and resistance increases with temperature. The law forms the basis for the definition of resistance, but it is not technically a law because it does not apply in all circumstances.

Electrical energy is carried through a circuit by electrons. The energy each electron has is called electric potential energy. It is measured in volts. Because electric potential energy is measured in volts, it is often called voltage. A voltmeter is a device that measures voltage. It can be connected onto the energy source or the load. When you connect the device to the positive and negative terminals of a battery, it measures the difference in volts between both sides.

It used to be thought that when an electric current flowed through a circuit, it was the positive charges which were moving. Now, we realize this is incorrect, and that the negative charges flow through a circuit. They flow from the negative terminal to the positive terminal of the energy force. The electric current from an electric cell flows in one direction. This is called direct current (DC). DC is used in battery-operated devices, such as watches. Alternating current (AC) is used in wall outlets. Alternating current occurs when the electrons periodically reverse direction. In a North American AC unit, the current reverses direction 60 times per second.

An ammeter measures the amount of electric current at a point in a circuit. It is connected in series with the circuit. A multimeter also measures current, among other things.

 We use current electricity all the time. Every time you turn on a light, turn on the oven, or even turn on a flashlight, you are using current electricity. Current electricity is electrical charges flowing in a circuit in a controlled way. An electrical circuit is a continuous path for energy to flow through.

A flashlight is a very simple electrical circuit. If you've taken it apart, you know there's not much to it. A switch to control a wire, two batteries, and a light bulb, contained inside a tube. The batteries are the energy source and the bulb is the load, the switch controls the flow of electricity, and wires to connect it all together. The joule (J) is the unit for measuring energy. A light bulb in a table lamp needs about 4000 J per minute it is on.

There are different sources of electrical energy. An electrical cell, for example, converts chemical energy into electrical. There are two types of electrical cells. Primary cells cannot be recharged. Secondary cells can. Two or more electrical cells is a battery. The load in an electrical device is what converts the energy into a different form. The light bulb in a flashlight, for example, converts the electrical energy into heat and light energy.

There are three ways an object can be charged. One is friction. If two objects are rubbed together, then some of the electrons will have a stronger attraction to one of the two objects, and some of the electrons will transfer over.Objects can also be charged through conduction. Charging by conduction occurs when objects touch and an electric charge is transferred. If you walk across a carpet and get a shock from touching a metal doorknob, this is from conduction.

Objects can also charge without any contact. When dust builds up on a computer screen, and the screen is turned on, the dust gathers a charge. When a neutral dust particle comes near the screen, the screen induces an opposite charge on the near side of the dust particle, attracting it to the screen.

Electricity is basically electrons moving quickly from atom to atom. An insulator is a substance in which the electrical charge cannot move to another object. Substances such as plastic, rubber, and glass are insulators. A conductor is on object through which an electrical charge passes easily. Most metals are good conductors. A semiconductor allows the electricity to travel through them, but not as easily.