# Must Know How To Use New Electric Circuits

#### CIRCUIT SCIENCE PROJECTS

Build a Circuit

How to make a circuit? A circuit is a path that electricity flows along. It starts at a power source, like a battery, and flows through a wire to a light bulb or other object and back to other side of the power source. You can build your own circuit and see how it works with this project

Insulator or Conductor?

Materials that electricity can flow through are call conductors. Materials that stop electricity from flowing are called insulators.

Before you test each object, guess whether it will make the light bulb light up or not. If it does, the object you’re touching the wires to is a conductor.

The light bulb lights up because the conductor completes, or closes, the circuit and electricity can flow from the battery to the light bulb and back to the battery! If it doesn’t light up, the object is an insulator and it stops the flow of electricity, just like an open circuit does. #### How to Make a Simple Electrical Circuit

Gather the necessary materials.

To build a simple circuit, you will need a power source, 2 insulated wires, a light bulb, and a light bulb holder. A power source can be any type of battery or battery pack. The rest of the materials can be found at your local hardware store.

Strip the ends of the insulated wires.

In order for your circuit to work properly, the wires need to be totally exposed so you must strip the ends. Using wire strippers, remove about 1 inch (2.5 cm) of the insulation from the ends of each wire.

Install batteries into the battery pack

Depending on the type of batteries you are using, you may be able to skip this step. If you are using multiple batteries, you will need a power pack to hold the batteries. Push each battery in by the side taking care to put the positive and negative ends in the correct orientation.

Attach your wires to the battery pack.

The wires will be conducting your electric current from the batteries to the light bulb. The easiest way to attach the wires is to use electrical tape. Attach the end of one wire to one side of the battery, making sure that the wire maintains contact with the metal of the battery. Repeat with the other wire on the other side of the battery.

Fasten the other end of the wire to the metal screw of the bulb holder.

Take the exposed metal end of each wire and bend it into a U-shape. Loosen each screw on the light bulb holder just enough to slip the U-shape of the wire around the screw. Each wire will be attached to its own screw. Tighten the screw, ensuring that the metal of the wires remains in contact with the screw.

#### Ohms Law and Power

Ohms Law Relationship

By knowing any two values of the Voltage, Current or Resistance quantities we can use Ohms Law to find the third missing value. Ohms Law is used extensively in electronics formulas and calculations so it is “very important to understand and accurately remember these formulas”.

Ohms Law Triangle

Then by using Ohms Law we can see that a voltage of 1V applied to a resistor of 1Ω will cause a current of 1A to flow and the greater the resistance value, the less current that will flow for a given applied voltage. Any Electrical device or component that obeys “Ohms Law” that is, the current flowing through it is proportional to the voltage across it ( I α V ), such as resistors or cables, are said to be “Ohmic” in nature, and devices that do not, such as transistors or diodes, are said to be “Non-ohmic” devices.

Electrical Power in Circuits

Electrical Power, ( P ) in a circuit is the rate at which energy is absorbed or produced within a circuit. A source of energy such as a voltage will produce or deliver power while the connected load absorbs it. Light bulbs and heaters for example, absorb electrical power and convert it into either heat, or light, or both. The higher their value or rating in watts the more electrical power they are likely to consume.

The Power Triangle

So we can see that there are three possible formulas for calculating electrical power in a circuit. If the calculated power is positive, (+P) in value for any formula the component absorbs the power, that is it is consuming or using power. But if the calculated power is negative, (–P) in value the component produces or generates power, in other words it is a source of electrical power such as batteries and generators.

Electrical Power Rating

Electrical components are given a “power rating” in watts that indicates the maximum rate at which the component converts the electrical power into other forms of energy such as heat, light or motion. For example, a 1/4W resistor, a 100W light bulb etc.

#### Physics Classroom – Home

If the two requirements of an electric circuit are met, then charge will flow through the external circuit. It is said that there is a current – a flow of charge. Using the word current in this context is to simply use it to say that something is happening in the wires – charge is moving. Yet current is a physical quantity that can be measured and expressed numerically. As a physical quantity, current is the rate at which charge flows past a point on a circuit. As depicted in the diagram below, the current in a circuit can be determined if the quantity of charge Q passing through a cross section of a wire in a time t can be measured. The current is simply the ratio of the quantity of charge and time.

Current is a rate quantity. There are several rate quantities in physics. For instance, velocity is a rate quantity – the rate at which an object changes its position. Mathematically, velocity is the position change per time ratio. Acceleration is a rate quantity – the rate at which an object changes its velocity. Mathematically, acceleration is the velocity change per time ratio. And power is a rate quantity – the rate at which work is done on an object. Mathematically, power is the work per time ratio. In every case of a rate quantity, the mathematical equation involves some quantity over time. Thus, current as a rate quantity would be expressed mathematically as

As is the usual case, when a quantity is introduced in The Physics Classroom, the standard metric unit used to express that quantity is introduced as well. The standard metric unit for current is the ampere. Ampere is often shortened to Amp and is abbreviated by the unit symbol A. A current of 1 ampere means that there is 1 coulomb of charge passing through a cross section of a wire every 1 second.

Conventional Current Direction

The particles that carry charge through wires in a circuit are mobile electrons. The electric field direction within a circuit is by definition the direction that positive test charges are pushed. Thus, these negatively charged electrons move in the direction opposite the electric field. But while electrons are the charge carriers in metal wires, the charge carriers in other circuits can be positive charges, negative charges or both. In fact, the charge carriers in semiconductors, street lamps and fluorescent lamps are simultaneously both positive and negative charges traveling in opposite directions.

Current versus Drift Speed

Current has to do with the number of coulombs of charge that pass a point in the circuit per unit of time. Because of its definition, it is often confused with the quantity drift speed. Drift speed refers to the average distance traveled by a charge carrier per unit of time. Like the speed of any object, the drift speed of an electron moving through a wire is the distance to time ratio. #### Residential Electrical Circuits Explained

What Are Electrical Circuits?

Before you put “electrical repair near me” in your favorite search engine, let’s make sure you understand what you’re looking for.

Power Circuits

If you need to transfer electricity as well as control it, you need a power circuit. When you install electrical wiring, this transfer is what you’re trying to accomplish. These are like the wiring systems in your residential home, but they can be as big as the power lines outside. If a large amount of electricity needs to be transferred and controlled, you’ll need power circuits to do it.

Electronic Circuits

Whereas power circuits are great for transferring and controlling electricity, they can’t do the same for information. That’s where electronic circuits come in. They come in many shapes and sizes. In fact, you probably have electrical circuits in your pocket right now. Cell phones are a perfect example of electronic circuits because of the amount of information flowing through that cell phone every day.

What Is a Circuit?

Now that we’ve made the distinction between a power circuit and an electronic circuit, what is a circuit anyway? In short, an electrical circuit is simply a pathway through which an electrical signal can travel. If electrons are allowed to travel from their source to their destination, your lights will light, your oven will heat, and your toaster will toast.

What Does It Mean When a Circuit Is Broken?

Just for the purpose of answering this question, picture a circuit as a circular train track. For the train to travel around that track, the track has to be continuous. Any break in the track and the train cannot continue.