Electric Current Electric Current The flow of Electricity

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Electric Current • Electric Current: The flow of Electricity along a path is called

Electric Current • Electric Current: The flow of Electricity along a path is called an Electric Current. • SI unit of Electric Current is Ampere (A). • Sources of Electricity: We get Electricity by • Burning Coal. • From Wind using Wind Mill • From Moving water using Turbines • From Sunlight using Solar Cells • From Chemicals using Cell or Battery • The Electric cell: • The Electric Cell is a simple source of electricity. • It produces electricity from reactions between chemicals. • It was invented by an Italian Scientists Alessandro Volta, in the year 1800.

Questions • Name the constituents of an Atom that can move. • What is

Questions • Name the constituents of an Atom that can move. • What is an Electric Bulb? • What makes an Electric Bulb glow? • Define: Electric Current. What is its SI unit? • Name different sources of Electricity. • What is an Electric Cell? How can it produce Electricity?

The Dry Cell • The Dry Cell: The cell which has Semi-Solid or Dry

The Dry Cell • The Dry Cell: The cell which has Semi-Solid or Dry chemicals is called Dry Cell. • Details: • A Dry cell is cylindrical in shape. It has a metal cap that is raised at one end a metal base with a groove or a depression at the other end. • Every cell has two ends, called Terminals. • The container is made of metal Zinc and is the Negative Terminal (marked as ‘-‘). • A metal cap is fitted on top (marked as ‘+’) and is connected to a carbon rod inside the cell which forms the Positive Terminal. • A Moist paste of chemicals (Ammonium Chloride and Manganese Di-Oxide) fills the space between the Carbon rod and the Zinc container. • A Dry cell is called a Primary cell. It has to be replaced after all the chemicals inside it are used up. • When the terminals are connected with wires, a chemical reaction produces an electric current. • In an electric cell, chemical energy is converted to electrical energy. • A collection of cells is called a Battery. • Other types of Cells: • Secondary or Storage cells: The cells which can be recharged again and again are called Secondary cell or Storage Cells. e. g. Car Battery, Laptop Battery, Solar Cells, Mobile Battery etc.

The Dry Cell • The Dry Cell: The cell which has Semi-Solid or Dry

The Dry Cell • The Dry Cell: The cell which has Semi-Solid or Dry chemicals is called Dry Cell. • Details: • A Dry cell is cylindrical in shape. It has a metal cap that is raised at one end a metal base with a groove or a depression at the other end. • Every cell has two ends, called Terminals. • The container is made of metal Zinc and is the Negative Terminal (marked as ‘-‘). • A metal cap is fitted on top (marked as ‘+’) and is connected to a carbon rod inside the cell which forms the Positive Terminal.

Dry Cell • A Moist paste of chemicals (Ammonium Chloride and Manganese Di-Oxide) fills

Dry Cell • A Moist paste of chemicals (Ammonium Chloride and Manganese Di-Oxide) fills the space between the Carbon rod and the Zinc container. • A Dry cell is called a Primary cell. It has to be replaced after all the chemicals inside it are used up. • When the terminals are connected with wires, a chemical reaction produces an electric current. • In an electric cell, chemical energy is converted to electrical energy. • A collection of cells is called a Battery.

Secondary Cell, Battery • Other types of Cells: • Secondary or Storage cells: The

Secondary Cell, Battery • Other types of Cells: • Secondary or Storage cells: The cells which can be recharged again and again are called Secondary cell or Storage Cells. e. g. Car Battery, Laptop Battery, Solar Cells, Mobile Battery etc.

Difference Between Primary Cell and Secondary Cell

Difference Between Primary Cell and Secondary Cell

Questions 1. What is electric Current? 2. What is an Electric Cell? 3. Can

Questions 1. What is electric Current? 2. What is an Electric Cell? 3. Can we connect an Electric Cell in a Torch in any arbitrary order? If no, why? 4. What is an Electrolyte? ? 5. Name the energy stored in a Dry Cell. 6. Name the chemicals used in a Dry Cell. 7. Differentiate between a Dry Cell and a Secondary cell.

Electric Bulb The Electric Bulb: An Electric Bulb uses electric current to provide light.

Electric Bulb The Electric Bulb: An Electric Bulb uses electric current to provide light. Details: An Electric Bulb has a thin, coiled wire called Filament, which is made of the metal Tungsten is used to make the filament because it has a high melting point. The ends of the filament are connected to two thick wires inside the bulb. One of the thick wires is connected to the base of the bulb and the other is connected to the metal case around the base. The base and the metal case around it form the two terminals of the bulb. The filament is enclosed in a transparent glass casing that is filled with an Inert gas (e. g. Argon). When electricity passes through the filament, it becomes so hot that it glows. The bulb is filled with an inert gas to prevent the Tungsten from evaporating or reacting with oxygen at high temperatures.

Electric Circuit Electric circuits: The closed path along electric current flows is called an

Electric Circuit Electric circuits: The closed path along electric current flows is called an Electric circuit. A simple Electric Circuit can be built with a Source of Current (an electric cell), a Bulb and Connecting Wires. A Bulb is connected to an Electric Circuit to show that electricity is flowing. Electricity flows from the Positive terminal of the cell to the Negative terminal of the cell through the Circuit.

Questions • What is a Dry Cell? • Who invented Electric Bulb? • Which

Questions • What is a Dry Cell? • Who invented Electric Bulb? • Which part of the Bulb gives off light? • Name the metal used to make the Filament of bulb and why is it used? • State the direction of current flow in an Electric circuit. • Why does the bulb of an Electric Bulb fill with inert gas?

Electric Switch The Electric Switch: An Electrical device which helps to control the flow

Electric Switch The Electric Switch: An Electrical device which helps to control the flow of current in an electric circuit is known as Switch. Details: In the ‘ON’ position, a switch makes an electric circuit complete. In the ‘OFF’ position, a switch breaks an electric circuit. A Switch helps us to ‘ON’ an electric circuit when needed and also helps us to ‘OFF’ the same when not needed.

Questions • Define: Electric Circuits. • Name three types of bulbs we use in

Questions • Define: Electric Circuits. • Name three types of bulbs we use in day to day life. • Name the device that is used to control flow of current in an electric current. • Give the symbol of electric bulb. • How do you minimise the time taken to draw an Electric Circuits?

Circuit Diagrams: The representation of an electrical circuit with the help of symbols is

Circuit Diagrams: The representation of an electrical circuit with the help of symbols is called a Circuit diagram. Sl No Component Symbol Sl No Components 1 Cell 4 Switch(Open) 2 Battery 5 Switch(Close 3 Bulb 6 d) Connecting Wires Symbo; l

Questions • What is an Electric Circuit? • State the energy conversion when a

Questions • What is an Electric Circuit? • State the energy conversion when a battery is connected to an Electric circuit. • Is it necessary to have Electric Circuit in every electric Gadget? • How do you test whether a material allows electricity to pass through it or not?

The Electric Torch: An Electric Torch is a device that produces light when required.

The Electric Torch: An Electric Torch is a device that produces light when required. Details: (i) An Electric Torch use a simple circuit to produce light. (ii)It generally has two cells connected to a small bulb. (iii) At the bottom of the Torch, the cells are connected to a spring. This ensures proper contact between the cells and the bulb. (iv) A switch on the outside helps to complete the circuit.

Conductors and Insulators: (i)Conductors: The materials through which electricity flows are known as Conductors

Conductors and Insulators: (i)Conductors: The materials through which electricity flows are known as Conductors of Electricity. e. g. Copper, Aluminum, Silver, Nichrome, Tungsten etc. (ii) Insulators: The materials through which electricity does not flow are known as Insulators of Electricity. e. g. Glass, Wood, Rubber, Plastic, Wool etc.

Activity: Aim of the Activity: To make a Conductivity Tester • Activity: Aim of

Activity: Aim of the Activity: To make a Conductivity Tester • Activity: Aim of the Activity: To make a Conductivity Tester • Materials required: A Bulb, A Cell, A Switch, Specimen to be tested and Connecting wires. • Procedure: (i) The Negative terminal of the Cell is connected to one terminal of the switch. • (ii) The other terminal of the switch is connected to one terminal of the specimen. • (iii) The other terminal of the specimen is connected to one terminal of the Bulb. • (iv) The other terminal of the bulb is connected to the Positive terminal of the cell to complete the circuit. • Observation: If the Bulb glows, then the given specimen is a conductor of Electricity.

Questions • What do you mean by Conductors? • Name the importance of the

Questions • What do you mean by Conductors? • Name the importance of the spring present in an Electric Torch. • Name the materials used to make Electric wires. • Should I handle a current carrying wire with wet hands? • List two uses each of Conductors and Insulators. • Why do the Tools used to repair electrical equipment have handles made of plastic? • What are the safety precautions to be taken while using an electric appliances?

Uses of Conductors and Insulators: Conductors: Conductors like copper and Aluminum are used to

Uses of Conductors and Insulators: Conductors: Conductors like copper and Aluminum are used to make electrical wires. Filaments of bulbs, the wires in switches, plug points and ends batteries are made of conductors. Insulators: Insulators like Plastic provide a protective coating over wires that carry electricity. Tools used to repair electrical equipment have handles made of plastic. This protects the electrician from getting electric shocks. All gadgets that run on electricity have a protective covering made of an insulator such as plastic or ceramic.

Safety measures while handling electricity: We should not handle electrical gadgets with wet hands.

Safety measures while handling electricity: We should not handle electrical gadgets with wet hands. Similarly we should not touch electric poles on the street, especially during the rainy days. We should not play with plug points and bare wires. One could get a shock. If someone receives an electric shock, they may not be able to pull themselves away from the source of electricity. We should not touch them directly or we will also get a shock too. We should turn off the switch to the equipment using an insulator. We should use fire extinguisher to put out a fire caused by an electrical fault.

One mark questions A. Multiple Choice questions 1. Which of the following does not

One mark questions A. Multiple Choice questions 1. Which of the following does not need electricity to function? (a) Exhaust Fan (b) Microwave Oven (c) Stapler (d) Mobile Phone 2. Why is the bulb of the electric bulb filled with an inert gas? (a) It does not react with Tungsten (b) It will not escape even if the bulb is broken (c) It can conduct Electricity (d) It glows when it is hot 3. A Circuit has an open switch. It means that ----------. (a) Current will flow in the circuit (b) the circuit is complete (c) both (a) and (b) (d) None of the above

Questions • What does this symbol stand for? • (a) A Connecting wire (b)

Questions • What does this symbol stand for? • (a) A Connecting wire (b) A closed switch (c) An Electric Cell (d) A Bulb • 5. The function of the spring at the base of the electric torch is to --------. • (a) Fill the space in the body of the Torch (b) Act as the negative terminal (c) Ensure proper connection in the Circuit (d) Act as the Positive terminal

Questions • What does this symbol stand for? • (a) A Cell (b) A

Questions • What does this symbol stand for? • (a) A Cell (b) A Closed switch (c) An Open switch (d) A Bulb • What does this symbol stand for? • (a) A Switch (b) A Battery (c) A Bulb (d) A Cell

Questions • B. Very Short answer Questions • Give one word for the following.

Questions • B. Very Short answer Questions • Give one word for the following. • The source of electricity in a torch • A Collection of Cells • The coiled metallic structure inside a bulb • A Device that controls the flow of current in a circuit • A material that does not allow current to pass through it • A material that allows current to pass through it • A Cell which produces electricity when sunlight falls on it.

1. Fill in the blanks. (i) A Collection of cells is called a -------------.

1. Fill in the blanks. (i) A Collection of cells is called a -------------. (ii) A material that allows electric current to pass through it is called --------- of electricity. (iii)The closed path along which electric current flows is called an --------- circuit. (iv)The representation of an electrical circuit with the help of symbols is called a -------diagram. (v) -------- is used in making the Filament of an Electric Bulb. (vi)Never handle electrical gadgets with ------- hands. (vii)Use a fire ----------- to put out a fire caused by an electrical fault. (viii)Do not use --------- to put out a fire caused by an electrical fault. (ix)In ----------- direction, the electric current comes out from the positive terminal.

1. Say whether the following statements are true or false? (i)An Electric cell converts

1. Say whether the following statements are true or false? (i)An Electric cell converts electrical energy to chemical energy. (ii)Solar cells use energy from sunlight to produce electricity. (iii)An Electric Bulb glows when connected to any one terminal of a cell only. (iv)A path through which current flows is made up of Conductors. (v)A Collection of Electric Cells is called a Battery. (vi)A Solar Cell can produce electricity on its own. (vii)The bulb of an electric bulb is filled with inert gas because it does not react with Tungsten.

Two marks questions 1. What are Conductors and Insulators? 2. What do you mean

Two marks questions 1. What are Conductors and Insulators? 2. What do you mean by Conventional and Actual directions of Electric Current? 3. What is an Electrical Wire? Why is Copper used to make Electrical Wires? 4. Which materials are used to make the Positive and Negative terminals of a Dry Cell? 5. What is a secondary Cell? Name two things that use a Secondary Cell. 6. List one uses each of Conductors and Insulators. 7. What is the use of an Inert gas in the Bulb of an Electric Bulb? When do we say that a Bulb is fuse? 8. What is a Filament? Name the Metal used in the Filament of an Electric Bulb. 9. What is the function of the spring at the base of the Electric Torch? Mention the role of Curved Reflecting Surface around the Bulb of an Electric Torch. 10. Name four things that use a Secondary cell.

Three marks questions 1. Differentiate between a Conductor and an Insulator. 2. Differentiate between

Three marks questions 1. Differentiate between a Conductor and an Insulator. 2. Differentiate between a Dry Cell and a Secondary Cell. 3. State the differences between an Electric Cell and a Battery. 4. Differentiate between a Closed Circuit and an Open Circuit. 5. What is the use of Electric Wire? List two uses each of Conductors and Insulators. 6. Describe an experiment to test whether a given material is a Conductor or an Insulator? 7. What is a Switch? Mention two safety precautions to be taken while using an Electric Oven? 8. Draw the symbols of (i) An Open Switch (ii) Electric bulb (iii) Connecting wires (iv) A Closed Switch (v) A Battery of four cells (vi) A Cell. 9. Name the Metal used in the Filament of an Electric Bulb. What is the use of an Inert gas in the Bulb of an Electric Bulb? When do we say that a Bulb is fuse? 10. What is Electric Current? What is an Electric Circuit? What is a Circuit Diagram?

Five marks questions 1. What is an Electric Cell? Draw and describe the parts

Five marks questions 1. What is an Electric Cell? Draw and describe the parts of an Electric cell. 2. What is an Electric bulb? Explain the structure and working of an Electric Bulb. 3. What is the use of Electric Wire? What are Conductors and Insulators? List two uses each of Conductors and Insulators. 4. What are Conductors and Insulators? Describe an experiment to test whether a given material is a Conductor or an Insulator? 5. What is Electric Current? What is an Electric cell? What is a Switch? Mention a difference between a Dry Cell and a Secondary Cell. Differentiate between a Closed Circuit and an Open Circuit. 6. What is an Electric Circuit? What is a Circuit Diagram? Draw the symbols of (i) An Open Switch (ii) Electric bulb (iii) Connecting wires (iv) A Closed Switch (v) A Battery of four cells (vi) A Cell. 7. What is a Bulb? What is a Filament? Name the Metal used in the Filament of an Electric Bulb. What is the use of an Inert gas in the Bulb of an Electric Bulb? When do we say that a Bulb is fuse? 8. What is an Electric Torch? Draw a neat and labeled diagram of an Electric Torch. 9. What is Electric Current? Draw the Flow Chart showing the current flow in a simple Electric Circuit. 10. What is Electric Current? What do you mean by Conventional and Actual directions of Electric Current? Differentiate between a Closed Circuit and an Open Circuit.