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# Electrical Components and Their Symbols

Grade 7
Aug 9, 2023

### Diagramming Circuits:

A simple circuit can be depicted by photographs or drawings of the parts. However, an electric circuit is most frequently drawn using standard symbols for the circuit elements. Such a diagram is called a circuit schematic diagram.

A schematic diagram of a circuit depicts the construction of an electrical apparatus. Reading a schematic diagram allows us to determine how the parts of an electrical device are arranged.

Each element used in a piece of electrical equipment is represented by a symbol in schematic diagrams that reflects the element’s construction or function.

## Electrical Components and their Symbols:

### Electric Wire or Conductor:

The electric wires that connect the circuit element are made of conductors. Because electric wires offer negligible resistance, they are represented by straight lines.

Fig-1: Electric wire and its symbol

### Resistor or Circuit Load:

A resistor is a two-terminal component used to reduce the current or divide voltage. Resistors are represented using multiple bends, illustrating resistance to the movement of charges.

Fig-2: A resistor and its symbol

### Bulb or Lamp:

The multiple bends of the filament indicate that the light bulb behaves as a resistor. The symbol for the filament of the bulb is often enclosed in a circle to emphasize the enclosure of a resistor in a bulb.

Fig-3: An electric bulb and its symbols

### Plug:

The plug symbol looks like a container for two prongs. The voltage difference between the two prongs of a plug is symbolized by lines of unequal length.

Fig-4: Plug and its symbol

### Battery:

A battery supplies power to an electric circuit. It is made of cells. It is a two-terminal device. In the symbol of a battery, the differences in the line’s length indicate a potential difference between the positive and negative terminals of the battery. The longer line represents the positive terminal, and the shorter line represents the battery’s negative terminal.

Fig-5: Battery and symbols for a single-cell and multiple-cell battery

### Switch:

The small circles indicate the two places where the switch makes contact with the wires. Most switches work by breaking only one of the contacts, not both.

Fig-6

### Capacitor:

A capacitor is used to store electrical energy or electrical charge. It is a two-terminal device made of two conductors separated by an insulator or a dielectric.

Fig-7: Capacitors and symbol for a fixed and variable capacitor

### Fuse:

A fuse is a safety device. It is used to protect an electric circuit in case of overloading and short circuits.

Fig-8: A fuse and its symbol

### Potentiometer or Variable Resistor:

A potentiometer is a three-terminal device. A potentiometer is a voltage divider used to measure electric potential (voltage) by varying the resistance.

Fig-9: A potentiometer and its symbol

### Inductor:

An inductor is a two-terminal electrical component that stores energy in a magnetic field when electric current flows through it.

Fig-10: An inductor and its symbol

### Ammeter:

An ammeter is a two-terminal device used to measure a current in a circuit. It is always connected in series to the battery in a circuit.

Fig-11: An ammeter and its symbol

### Voltmeter:

A voltmeter is a two-terminal device used to measure a potential difference or voltage in a circuit. It is always connected parallel to the battery in a circuit.

Fig-12: A voltmeter and its symbol

### Galvanometer:

A galvanometer is a two-terminal device used to detect the presence of current and change the direction of the flow of current.

Fig-13: A galvanometer and its symbol

Question-1: Represent the following closed circuit using circuit symbols.

Answer-1: The closed circuit can be represented in a simple way using the symbols for the circuit components in the following way, as shown in the figure below.

Question 2: What are the electrical components in the given circuit diagram? Identify them and draw their circuit symbols.

Answer-2

#### Electric Circuit:

Any closed-loop or conducting path allowing electric charges to flow is called an electric circuit.

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