Electric Circuit
Electric Circuit
An electric circuit is a path that allows electricity to flow. It consists of a source of electrical energy, such as a battery, and a load, such as a light bulb. The source of energy provides the voltage, or electrical pressure, that causes the current, or flow of electrons, to move through the circuit. The load uses the electrical energy to perform a task, such as lighting a light bulb. Circuits can be simple, with just a few components, or complex, with many components. They can be used in a variety of applications, from small electronic devices to large power systems.
Electric Circuit
Electric Circuit
An electric circuit is a path that allows electricity to flow. It consists of a source of electrical energy, such as a battery, and a load, such as a light bulb. The source of energy provides the electrical potential difference, or voltage, that causes the current to flow. The load consumes the electrical energy and converts it into another form, such as light or heat.
Components of an Electric Circuit
The basic components of an electric circuit are:
 Source of electrical energy: This can be a battery, a generator, or another device that provides the voltage to drive the current.
 Load: This is the device that consumes the electrical energy and converts it into another form.
 Conductors: These are materials that allow electricity to flow easily. They are typically made of metals, such as copper or aluminum.
 Insulators: These are materials that do not allow electricity to flow easily. They are typically made of plastics or rubber.
Types of Electric Circuits
There are two main types of electric circuits:
 Series circuits: In a series circuit, the components are connected in a single loop. The current flows through each component in turn, and the total resistance of the circuit is the sum of the resistances of the individual components.
 Parallel circuits: In a parallel circuit, the components are connected in multiple loops. The current can flow through any of the loops, and the total resistance of the circuit is less than the resistance of any of the individual components.
Examples of Electric Circuits
Some common examples of electric circuits include:
 Lighting circuits: These circuits provide power to light bulbs.
 Power circuits: These circuits provide power to appliances, such as refrigerators and washing machines.
 Control circuits: These circuits control the operation of devices, such as thermostats and security systems.
Electric circuits are used in a wide variety of applications, from simple devices to complex systems. They are essential for the functioning of our modern world.
Electricity and Circuits Complete Chapter Revision Class 6
Chapter Revision: Electricity and Circuits (Class 6)
1. Electric Current:
 Electric current is the flow of electric charges through a conductor.
 It is measured in amperes (A).
 Example: When you switch on a light, electric current flows from the battery or power source through the wires and the bulb, causing it to light up.
2. Circuits:
 A circuit is a closed loop that allows electric current to flow.
 There are two types of circuits: series circuits and parallel circuits.
 In a series circuit, the components are connected in a single pathway, so the current has only one path to follow.
 In a parallel circuit, the components are connected in multiple pathways, so the current has multiple paths to follow.
3. Components of a Circuit:
 A circuit consists of several components, including:
 A source of electrical energy (e.g., battery, power supply)
 Conductors (e.g., wires)
 Loads (e.g., bulbs, motors)
 Switches
 Fuses
4. Ohm’s Law:
 Ohm’s law states that the current flowing through a conductor is directly proportional to the voltage applied across it, and inversely proportional to the resistance of the conductor.
 It is expressed as: I = V/R, where I is the current, V is the voltage, and R is the resistance.
5. Resistance:
 Resistance is the opposition to the flow of electric current.
 It is measured in ohms (Ω).
 The resistance of a conductor depends on its material, length, and crosssectional area.
6. Power:
 Power is the rate at which electrical energy is transferred or consumed.
 It is measured in watts (W).
 The power consumed by a device is calculated as: P = VI, where P is the power, V is the voltage, and I is the current.
7. Safety Precautions:
 Always handle electrical appliances with dry hands.
 Never touch exposed wires or electrical outlets.
 Do not overload electrical outlets.
 Use properly insulated wires and cables.
 Keep electrical appliances away from water.
Examples:
 A simple circuit can be created by connecting a battery, a bulb, and a switch in series. When the switch is closed, the circuit is complete and the bulb lights up.
 A parallel circuit can be created by connecting multiple bulbs in parallel with each other. When the switch is closed, all the bulbs light up independently.
 Ohm’s law can be demonstrated using a battery, a voltmeter, an ammeter, and a resistor. By varying the resistance of the resistor, the relationship between voltage, current, and resistance can be observed.
Electric Circuit Symbols
Electric circuit symbols are graphical representations of various components used in electrical circuits. They provide a standardized way to represent and understand the functionality of different elements within a circuit diagram. Here are some commonly used electric circuit symbols along with their explanations and examples:

Battery Symbol:
 Represents a source of electrical energy.
 Symbol: A rectangle with a “+” sign at one end and a “” sign at the other end.
 Example: A 9volt battery used to power a flashlight.

Resistor Symbol:
 Represents a component that resists the flow of electric current.
 Symbol: A zigzag line.
 Example: A 100ohm resistor used to limit current flow in a circuit.

Capacitor Symbol:
 Represents a component that stores electrical energy in an electric field.
 Symbol: Two parallel lines with a small gap between them.
 Example: A 100microfarad capacitor used to store charge in a circuit.

Inductor Symbol:
 Represents a component that stores electrical energy in a magnetic field.
 Symbol: A coil of wire.
 Example: A 1henry inductor used to store energy in a circuit.

Diode Symbol:
 Represents a component that allows current to flow in only one direction.
 Symbol: A triangle with a line perpendicular to one side.
 Example: A 1N4007 diode used to prevent reverse current flow in a circuit.

Transistor Symbol:
 Represents a semiconductor device that can amplify or switch electronic signals.
 Symbol: A vertical line with two or three horizontal lines connected to it.
 Example: A 2N3904 transistor used as an amplifier in an audio circuit.

Switch Symbol:
 Represents a mechanical device that can open or close a circuit.
 Symbol: A circle with a line cutting through it.
 Example: A light switch used to control the flow of current to a light bulb.

Ground Symbol:
 Represents a reference point for electrical potential in a circuit.
 Symbol: A horizontal line with a vertical line connected to it.
 Example: The ground terminal of an electrical outlet.
These are just a few examples of electric circuit symbols. There are many other symbols used to represent various components and devices in electrical circuits. By understanding these symbols, you can easily read and interpret circuit diagrams, which are essential for designing, analyzing, and troubleshooting electrical systems.
Simple Circuit
A simple circuit is a closed loop that allows electricity to flow. It consists of a source of electrical energy, such as a battery, and a load, such as a light bulb. The source of energy provides the electrical potential, or voltage, that causes the electrons to flow through the circuit. The load provides the resistance, or opposition to the flow of electrons.
The simplest circuit is a series circuit, which is a circuit in which the components are connected in a single loop. In a series circuit, the current flows through each component in turn. The total resistance of a series circuit is the sum of the resistances of the individual components.
A parallel circuit is a circuit in which the components are connected in multiple loops. In a parallel circuit, the current can flow through any of the loops. The total resistance of a parallel circuit is less than the resistance of any of the individual components.
Here is an example of a simple series circuit:
[Image of a simple series circuit]
In this circuit, the battery is the source of electrical energy. The light bulb is the load. The wires connect the battery to the light bulb.
When the switch is closed, the circuit is complete and the electrons can flow from the battery, through the light bulb, and back to the battery. The light bulb will light up.
Here is an example of a simple parallel circuit:
[Image of a simple parallel circuit]
In this circuit, the battery is the source of electrical energy. The light bulbs are the loads. The wires connect the battery to the light bulbs.
When the switch is closed, the circuit is complete and the electrons can flow from the battery, through any of the light bulbs, and back to the battery. Both light bulbs will light up.
Simple circuits are used in a wide variety of applications, from small electronic devices to large power systems.
Frequently Asked Questions – FAQs
What is an electric circuit?
Electric Circuit
An electric circuit is a path that allows electricity to flow. It consists of a source of electrical energy, such as a battery, and a load, such as a light bulb. The source of electrical energy provides the power to push the electrons through the circuit, and the load uses the electrical energy to do work.
There are two types of electric circuits: series circuits and parallel circuits. In a series circuit, the components are connected in a single loop, so the current flows through each component in turn. In a parallel circuit, the components are connected in multiple loops, so the current can flow through any of the components at the same time.
Series Circuits
In a series circuit, the current flows through each component in turn. This means that the total resistance of the circuit is the sum of the resistances of the individual components. The total voltage of the circuit is the same as the voltage of the source.
For example, consider a series circuit with a battery, a light bulb, and a resistor. The battery has a voltage of 12 volts, the light bulb has a resistance of 6 ohms, and the resistor has a resistance of 3 ohms. The total resistance of the circuit is 6 + 3 = 9 ohms. The total voltage of the circuit is 12 volts.
The current flowing through the circuit can be calculated using Ohm’s law:
I = V/R
where:
 I is the current in amps
 V is the voltage in volts
 R is the resistance in ohms
In this example, the current flowing through the circuit is 12 volts / 9 ohms = 1.33 amps.
Parallel Circuits
In a parallel circuit, the components are connected in multiple loops, so the current can flow through any of the components at the same time. This means that the total resistance of the circuit is less than the resistance of any of the individual components. The total voltage of the circuit is the same as the voltage of the source.
For example, consider a parallel circuit with a battery, two light bulbs, and two resistors. The battery has a voltage of 12 volts, the light bulbs each have a resistance of 6 ohms, and the resistors each have a resistance of 3 ohms. The total resistance of the circuit is:
1/Rtotal = 1/R1 + 1/R2 + 1/R3 + 1/R4
where:
 Rtotal is the total resistance of the circuit
 R1, R2, R3, and R4 are the resistances of the individual components
In this example, the total resistance of the circuit is:
1/Rtotal = 1/6 + 1/6 + 1/3 + 1/3
Rtotal = 2 ohms
The total voltage of the circuit is 12 volts.
The current flowing through each component can be calculated using Ohm’s law:
I = V/R
where:
 I is the current in amps
 V is the voltage in volts
 R is the resistance in ohms
In this example, the current flowing through each light bulb is 12 volts / 6 ohms = 2 amps. The current flowing through each resistor is 12 volts / 3 ohms = 4 amps.
Applications of Electric Circuits
Electric circuits are used in a wide variety of applications, including:
 Lighting
 Heating
 Cooling
 Transportation
 Communication
 Computing
Electric circuits are essential to our modern way of life. They make it possible for us to power our homes and businesses, communicate with each other, and travel from place to place.
What is a switch?
What is a Switch?
A switch is a networking device that connects multiple devices on a computer network. It operates at layer 2 of the OSI model, which is the data link layer. Switches are used to forward data packets between devices on the network, based on the destination MAC address of each packet.
Switches are more advanced than hubs, which simply forward all packets to all devices on the network. Switches learn which devices are connected to each port, and they only forward packets to the ports that need to receive them. This reduces the amount of unnecessary traffic on the network, which can improve performance.
Switches can be used to connect a variety of devices, including computers, printers, servers, and other network devices. They can also be used to create virtual LANs (VLANs), which allow you to segment your network into multiple logical networks.
How Switches Work
Switches work by using a process called MAC address learning. When a switch receives a packet, it reads the destination MAC address of the packet and compares it to the MAC addresses of the devices that are connected to its ports. If the switch finds a match, it forwards the packet to the corresponding port. If the switch does not find a match, it floods the packet to all of its ports, except for the port that it received the packet from.
Over time, the switch learns which devices are connected to each port, and it builds a MAC address table. This table allows the switch to forward packets more efficiently, without having to flood them to all of its ports.
Types of Switches
There are a variety of different types of switches, including:
 Unmanaged switches: These switches are the most basic type of switch, and they do not offer any configuration options. They are typically used in small networks where there is no need for advanced features.
 Managed switches: These switches offer a variety of configuration options, such as VLAN support, port security, and traffic prioritization. They are typically used in larger networks where there is a need for more control over the network traffic.
 Layer 3 switches: These switches operate at layer 3 of the OSI model, which is the network layer. They can route packets between different networks, and they can also perform other advanced functions, such as firewalling and load balancing.
Benefits of Using Switches
Switches offer a number of benefits over hubs, including:
 Improved performance: Switches reduce the amount of unnecessary traffic on the network, which can improve performance.
 Increased security: Switches can be used to segment your network into multiple VLANs, which can help to improve security.
 Scalability: Switches can be used to connect a large number of devices, and they can be easily scaled to meet the needs of a growing network.
Conclusion
Switches are an essential part of any modern computer network. They provide a number of benefits over hubs, including improved performance, increased security, and scalability. If you are looking for a way to improve the performance of your network, or if you need to connect a large number of devices, then a switch is a great option.
Examples of Switches
Here are some examples of switches that are available on the market:
 Cisco Catalyst 2960 Series Switches: These switches are a popular choice for small businesses and enterprise networks. They offer a variety of features, including VLAN support, port security, and traffic prioritization.
 HP ProCurve 1800 Series Switches: These switches are a good choice for small businesses and home offices. They offer a variety of features, including VLAN support, port security, and traffic prioritization.
 Netgear GS724T Smart Managed Switch: This switch is a good choice for small businesses and home offices. It offers a variety of features, including VLAN support, port security, and traffic prioritization.
What is the formula to calculate electric current?
Electric Current Formula
The formula to calculate electric current (I) is:
I = Q / t
Where:
 I is the electric current in amperes (A)
 Q is the electric charge in coulombs (C)
 t is the time in seconds (s)
Example 1:
If a charge of 10 coulombs flows through a conductor in 5 seconds, the electric current is:
I = Q / t = 10 C / 5 s = 2 A
Example 2:
If an electric current of 3 amperes flows through a conductor for 10 seconds, the electric charge that flows through the conductor is:
Q = I * t = 3 A * 10 s = 30 C
Example 3:
If a charge of 12 coulombs flows through a conductor in 3 seconds, the average electric current is:
I = Q / t = 12 C / 3 s = 4 A
However, if the current is not constant, the average current can be calculated by dividing the total charge by the total time, even if the current varies during that time.
Example 4:
If a varying current flows through a conductor and the total charge that flows through the conductor in 10 seconds is 20 coulombs, the average electric current is:
I = Q / t = 20 C / 10 s = 2 A
Note:
The electric current is a scalar quantity, which means that it has only magnitude and no direction. The direction of the current is determined by the direction of the flow of positive charge.
When is an electric circuit said to be complete?
An electric circuit is considered complete when it provides a continuous path for the flow of electric current. In simpler terms, when there is a closed loop or pathway that allows electricity to move freely without any breaks or interruptions, the circuit is said to be complete.
Here are some key points to understand when an electric circuit is complete:

Closed Loop: A complete circuit must have a closed loop or pathway for the current to flow. This means that the circuit should form a continuous path without any gaps or breaks.

Power Source: A complete circuit requires a power source, such as a battery or a power outlet, to provide the electrical energy needed to drive the current. The power source establishes a potential difference or voltage across the circuit.

Load or Resistor: A complete circuit must include a load or resistor, which consumes or utilizes the electrical energy provided by the power source. The load can be a light bulb, a motor, a resistor, or any other device that offers resistance to the flow of current.

Conducting Path: The circuit must have a conducting path, typically made of metal wires or other conductive materials, that connects the power source, the load, and any other components in the circuit. These conducting wires allow the electric current to flow freely.

Switches or Controls: Switches or control devices can be included in a complete circuit to regulate the flow of current. When a switch is closed, it completes the circuit, allowing the current to flow. When the switch is open, it breaks the circuit, interrupting the flow of current.
Examples of Complete Circuits:

Simple BatteryBulb Circuit: A simple circuit consists of a battery, a light bulb, and connecting wires. When the wires are connected to form a closed loop, with the battery and the bulb in series, the circuit is complete. The battery provides the power, the bulb acts as the load, and the wires provide the conducting path. When the circuit is complete, the bulb lights up.

Household Lighting Circuit: In a household lighting circuit, the power source is the electrical outlet, the load is the light bulb, and the conducting path is the electrical wiring in the walls. When the light switch is turned on, it completes the circuit, allowing the current to flow and the light bulb to illuminate.

Electrical Appliances: Various electrical appliances, such as toasters, refrigerators, and computers, have complete circuits within them. These circuits include power cords, internal wiring, switches, and components that work together to provide the necessary electrical energy to operate the appliance.
In summary, an electric circuit is complete when it has a continuous pathway for the flow of electric current, including a power source, a load or resistor, conducting wires, and any necessary control devices. When the circuit is complete, electricity can flow freely, powering devices and enabling them to perform their intended functions.
What is the formula to calculate power?
Power Formula
The formula to calculate power is:
Power = Work / Time
Where:
 Power is measured in watts (W)
 Work is measured in joules (J)
 Time is measured in seconds (s)
Example 1:
A person lifts a 10kg box a vertical distance of 1 meter in 2 seconds. The power required to do this work is:
Power = Work / Time
Power = (10 kg * 9.8 m/s^2 * 1 m) / 2 s
Power = 49 W
Example 2:
A 100watt light bulb is turned on for 1 hour. The energy consumed by the light bulb is:
Energy = Power * Time
Energy = (100 W * 1 h)
Energy = 100 Wh
Example 3:
A car engine produces 200 horsepower. The power output of the engine is:
Power = 200 hp * 746 W/hp
Power = 149,200 W