Electricity and Circuits - Class 6 Notes & Olympiad Questions

Electricity

a) Electricity is a form of energy that powers many of the things we use in our daily lives.
b) We rely on electricity for numerous purposes both in our homes, industries and even in transportation.
c) It is an essential component that surrounds us, from the natural phenomenon of lightning in the sky to the comforting warmth of heaters in our homes.
d) The electricity we utilise within our households and industries is supplied by power stations.
e) Electricity flows through wires, just like water flows through pipes. When we want to use electricity, we need to create a pathway for it to travel. This pathway is called an electric circuit.

Electric Current

a) In our homes, we have outlets where we can plug in devices like phones, lamps, or televisions. When we plug something in, we complete the circuit, and the electricity starts flowing from the power source (like a power station) to the device we're using.
b) This flow of electric charges in a circuit is what we call an electric current.
c) In the world of electricity, we have two types of charges: positive and negative charges.
d) Just like magnets, where similar poles repel each other and opposite poles attract, electric charges behave in a similar way. This means that positive charges repel other positive charges, and negative charges repel other negative charges. But, positive and negative charges attract each other.

Electric Circuit

a) An electric circuit is like a path that allows electric current to flow in a complete loop. It's made up of different elements like electric bulbs, electric cells (or batteries), electric switches, and wires.
b) When we connect these elements together in a closed loop, it forms a circuit. This means that the current can travel from one point to another in a continuous pathway.
c) It's important to note that the circuit needs to be closed for the current to flow. This means that all the components of the circuit, like the wires and the switch, need to be properly connected so that there is a continuous pathway for the current to follow.
d) In a circuit, the electric current flows from the positive terminal of the electric cell (or battery) to the negative terminal. The electric cell provides the energy or "push" needed to make the electric charges move around the circuit.

Electric Components

Electric Cell

a) An electric cell is a special device that acts as a source of electricity. The primary job of an electric cell is to convert chemical energy, which is stored inside the cell, into electrical energy that we can use.
b) An electric cell has two terminals, which are like the cell's "endings" or "connections." One of these terminals is usually marked with a metal cap and is called the positive terminal. The other terminal is marked with a metal disc and is known as the negative terminal.
c) Inside the cell, there are chemicals that can produce electricity. These chemicals are carefully chosen and combined in such a way that they create a chemical reaction when the cell is in use.
d) This reaction generates electrical energy and allows the flow of electric charges, creating an electric current.

Classification of Cells

1. Primary Cells

a) Some cells, called primary cells, are designed to be used once.
b) When all the chemicals inside the cell are used up, it stops producing electricity, and we replace it with a new cell.
c) These types of cells are used in household devices like remote controls or flashlights.

2. Secondary Cells

a) On the other hand, there are cells that can be recharged and used multiple times. We call these secondary cells.
b) They can be recharged by sending electrical energy back into them, which replenishes the chemicals inside and allows them to produce electricity again.
c) Examples of secondary cells include the batteries used in smartphones, laptops, and electric vehicles.

Types of Cells

There are different types of electric cells and each type serves a specific purpose and has different characteristics.

1. Dry Cells

a) Dry cells are commonly used in everyday devices like flashlights, remote controls, and portable radios.
b) They are called "dry cells" because they don't contain liquid or fluid. Inside a dry cell, there is a chemical paste or gel that acts as a source of electrical energy.
c) Dry cells are convenient because they are portable, easy to use, and don't require special maintenance.

2. Car Battery

a) A car battery is a special type of electric cell used to power vehicles like cars and motorcycles.
b) It is much larger and more powerful than a dry cell.
c) Car batteries are rechargeable, meaning they can be recharged and used multiple times.
d) They have a higher capacity to provide a large amount of electrical energy to start the car's engine and power various electrical systems in the vehicle.

3. Solar Cell

a) A solar cell, also known as a photovoltaic cell, is a unique type of electric cell that converts sunlight directly into electricity.
b) Solar cells are used in solar panels to generate renewable energy from the sun.
c) They are environmentally friendly and are an important source of clean energy.

4. Button Cell

a) Button cells are small, round-shaped electric cells commonly used in devices like watches, calculators, and hearing aids.
b) They are called "button cells" because of their shape, which resembles a small button.
c) Button cells are often non-rechargeable and are sealed inside a metal casing.
d) They provide a stable and long-lasting source of electrical power for small electronic devices that require low energy.

Battery

a) When multiple cells are connected together, they form a battery.
b) A battery is like a team of cells working together to provide more electrical energy.
c) Batteries come in different sizes and shapes, depending on the number and type of cells they contain.

Electric Switch

a) An electric switch is a device that we use in an electric circuit to control the flow of electric current. It's like a gate that can either allow or block the movement of the electric charges.
b) An electric switch can either be ON or OFF.
c) When the switch is ON, it acts like an open door in the circuit. It allows the electric current to flow smoothly through the circuit.
d) On the other hand, when the switch is OFF, it acts like a closed door. It blocks the flow of electric current in the circuit.
e) By turning the switch ON or OFF, we can control the flow of electric current and determine whether a device connected to the circuit receives power or not.
f) For example, if you have a lamp connected to a circuit with a switch, turning the switch ON will allow the electric current to flow, and the lamp will light up. But if you turn the switch OFF, the current will be blocked, and the lamp will turn off.
g) Electric switches are an essential part of our electrical systems, as they give us the ability to control when and where electricity flows. They make it convenient and safe to use electrical devices and conserve energy when we don't need them.

Electric Fuse

a) An electric fuse is a device that helps protect electrical circuits from overloading and keeps our devices safe when there's too much current flowing through a circuit.
b) Imagine you have a water pipe that can only handle a certain amount of water flowing through it. If you try to force more water through the pipe than it can handle, it might burst or cause damage. Similarly, in an electric circuit, too much current can be dangerous and can damage the circuit or the connected devices.
c) To prevent this, we use an electric fuse, also known as a circuit breaker. It is connected in a line with the other parts of the circuit. The fuse is a small, thin wire that is designed to melt or break when too much current passes through it.
d) The fuse has a rating which tells us the maximum amount of current it can handle. If the current flowing through the circuit exceeds the rating of the fuse, the fuse wire will melt and break the circuit.
e) Using a fuse in a circuit is important because it helps ensure the safety and longevity of electrical devices.

Electric Bulb

a) An electric bulb, also known as a light bulb, is a device that produces light when an electric current flows through it.
b) Inside the bulb, there is a thin wire called a filament. This filament is made of a special material that can get very hot without melting. When an electric current passes through the filament, it gets heated up and starts glowing, giving off light.
c) The outer case of the bulb is usually made of glass, which protects the filament and allows the light to shine through.
d) Sometimes, if the bulb doesn't glow, it could be because the filament inside has fused or broken. This can happen when the filament gets too hot due to a high amount of current flowing through it or if it has been used for a long time. When the filament breaks, the circuit is interrupted, and the current can no longer flow through it, resulting in the bulb not producing light.
e) When a bulb stops working, we need to replace it with a new one because the filament cannot be repaired. However, modern bulbs, such as LED bulbs, have different mechanisms and don't rely on a heated filament. They are more durable and energy-efficient.
f) Electric bulbs are widely used in our homes, schools, and offices to provide artificial light.

Conductors and Insulators

In the world of electricity, there are two important materials: conductors and insulators.

Conductors

a) Conductors are materials that let electric current flow through them easily.
b) Some examples of conductors are metals like copper, silver, and aluminium.
c) We use copper wires in a circuit because copper is a great conductor. It allows electric charges to move freely.

Insulators

a) Insulators are materials that don't let the electric current pass through them easily. They act like barriers to electricity.
b) Some examples of insulators are wood, plastic, glass, and leather. These materials don't allow electric charges to move around easily, so they help keep us safe from shocks.

Understanding conductors and insulators help us know which materials are good for carrying electricity and which ones are better for keeping it contained or controlled.