Samacheer Class 6 Science - Electricity

In a parallel circuit, electricity has more than one path – True. To make a battery of two cells, the negative terminal of one cell is connected to the positive terminal of the other cell – True. The switch is used to close or open an electric circuit – True. Pure water is a good conductor of electricity – False, pure water is an insulator because it lacks ions; only impure water containing dissolved salts is a conductor. Secondary cells can be used only once – False, secondary cells can be recharged and used many times, unlike primary cells which can be used only once.

Yes, we can produce electricity from a lemon using it as a simple electrochemical cell. To create a lemon cell, insert a copper plate on one side of the lemon and a zinc strip or safety pin on the other side. The lemon juice acts as an electrolyte containing ions that allow chemical reactions to occur between the two different metals. The copper plate serves as the positive terminal and the zinc strip or safety pin serves as the negative terminal. When you connect the two terminals with connecting wires to an electric bulb or other load, a small electric current flows through the circuit due to the chemical reaction inside the lemon. This current is sufficient to make a small bulb glow dimly. Multiple lemon cells can be connected in series to produce greater voltage and brightness. This demonstrates how chemical energy can be converted into electrical energy.

The cell used in the clock will not give us an electric shock because the voltage of that cell is very low nearly 1.5 v.
So it will not affect our body.

In thermal power stations, thermal energy is generated by burning coal, diesel, or gas to produce steam.
Steam is used to rotate the turbine to generate electricity.
Here heat energy is converted into electric energy.
Hydel power stations:
In hydel power stations, the turbine is made to rotate by the flow of water from dams.
Here kinetic energy is converted into electric energy.
Atomic power station:
Here nuclear energy is used to boil water
The steam thus produced is used to rotate the turbine, as a result, electricity is produced.
Here nuclear energy is converted into mechanical energy.
Windmills:
In windmills, wind energy is used to rotate turbines to produce electricity.
Here kinetic energy is converted into electrical energy.

Conductors are materials that allow electric charges to pass through them easily. The rate of flow of electric charges in a circuit is called electric current. Conductors have free electrons that can move readily when a potential difference is applied, enabling the flow of electricity. Common examples of conductors include copper, aluminum, iron, silver, and impure water. These materials are widely used in electrical applications because of their ability to conduct electricity efficiently. Insulators or non-conductors are materials that do not allow electric charges to pass through them. They have electrons that are tightly bound to atoms and cannot move freely, preventing the flow of electricity. Common examples of insulators include plastic, rubber, glass, wood, porcelain, ebonite, and pure water. Insulators are used to cover and protect conductors in electrical wires and devices to prevent electric shock and ensure safety. The difference between conductors and insulators is fundamental to the design and safety of all electrical systems.

Yes, the bulb will glow. Rahul can use a lemon as a substitute for a battery to complete his electric circuit. He should insert the copper piece into the lemon on one side and the safety pin into the lemon on the opposite side. The lemon juice acts as an electrolyte containing ions that facilitate a chemical reaction between the two different metals. The copper piece serves as the positive terminal and the safety pin serves as the negative terminal of this lemon cell. By connecting the two connecting wires to these terminals and then connecting them to the bulb, an electric circuit is formed. The chemical reaction inside the lemon produces a small electric current that flows through the circuit. Although the current from a single lemon cell is weak, it is sufficient to make the bulb glow, though the glow may be dim. This simple experiment demonstrates how electrical energy can be generated from chemical reactions and how a basic electric circuit works.

In thermal power stations, electricity is produced through a series of energy conversions. Coal is burned in a furnace, and the thermal energy released heats water to produce steam at high temperature and pressure. This high-pressure steam is directed onto the blades of a turbine, causing it to rotate at high speed. The rotating turbine is connected to a generator containing a coil of wire positioned between the poles of a powerful electromagnet. As the turbine rotates, the coil rotates within the magnetic field of the electromagnet. Due to electromagnetic induction, a changing magnetic flux passes through the rotating coil, which induces an electric current in the coil. This induced current is then transmitted through power lines to homes and industries. The process converts chemical energy in coal into thermal energy, then into mechanical energy of the rotating turbine, and finally into electrical energy through electromagnetic induction.

Several important safety measures should be followed to safeguard a person from electric shock. First, immediately switch off the power supply to cut off the source of electricity. Second, remove the connection from the switch or circuit breaker to ensure the circuit is completely open. Third, if the person is still in contact with the electrical source, push them away using non-conducting materials such as wooden sticks, rubber, or dry cloth to avoid becoming a victim yourself. Fourth, once the person is away from the electrical source, provide first aid by checking their breathing and pulse, and if necessary, perform cardiopulmonary resuscitation. Finally, take the person to the nearest health centre or hospital immediately for professional medical treatment and evaluation. Never touch an electrocuted person directly with bare hands while they are still in contact with the electrical source, as this can cause you to also receive a shock.