Introduction to Energy around a Circuit

Key Concepts

• Electric circuit
• Electric load
• Conventional current
• Open circuit
• Closed circuit

Introduction: 

When you feel hot, you switch on the fan. When you want to study, you switch on the light. Just a single click on the switch makes everything possible. But, how is this happening? In this section you are going to learn about electric circuits. You will make an electric circuit. Based on the flow of electrons, you will identify whether the electric circuit is closed circuit or an open circuit. Also, the direction of flow of electrons and charges will be understood in detail. 

Explanation: 

Electric circuit: 

A complete pathway that allows electrons to flow is called an electric circuit. The components included in an electric circuit are a battery, connecting wires, a switch and an electric load.  

Electric load is an electrical component which converts electrical energy into other forms of energy. Example: Buzzer, heater, motor, computer, fan, light bulb, AC, TV and many more. 

As seen in the electric circuit in figure 1, the electric bulb converts the electrical energy into heat energy and light energy. 

Open circuit: 

The chemical energy in the battery is converted to electrical energy which flows in the electric circuit. The electrons released from the battery move from the negative terminal of the battery through the connecting wires towards the positive terminal of the battery.  

In case if any insulator is present in the electric circuit or there is a break in the circuit then electrons will stop there and will not flow further. Such type of electric circuit is known as an open circuit.  

Close circuit;

In a closed electric circuit, electrons are released from the negative terminal. These electrons are attracted towards the positive end of the battery. Since a wire is a conductor, it helps in the conduction of electrons from the negative end of the battery to the positive end. This wire is connected to the bulb in between which acts as an electric load and converts this electrical energy into light energy. 

This way the electrons travel to the negative terminal and the electric circuit is complete.  

Convectional current: 

In 1747, Benjamin Franklin wrote that charges flow from positive terminal of the battery to the negative terminal of the battery. Electrons were discovered much later in the 1800’s, so we still take the direction of current from positive terminal of the battery to the negative terminal. This current is known as “conventional current.”

Questions and answers 

Question 1: Draw an open electric circuit using bulb, battery and wire. 

Answer:

Question 2:  Draw a closed electric circuit using bulb, battery and wire.  

Answer:

Summary

• Electric circuit – a complete pathway that allows electrons to flow.
• Electric load Any device that transforms electrical energy into other forms of energy.
• Electrons flow from negative terminal of the battery to the positive terminal.
• Conventional current flows from positive terminal to the negative terminal of the battery.
• An electric circuit is said to be:

a. Closed-when there can be no breaks in the paths of electrons

b. Open when there can be breaks in the paths of electrons.