Table of Contents

Toggle**Electricity class 10 notes**

**Definition of Electricity:**

Electricity is the flow of electric charge, often carried by electrons, through a conductor (wire), creating electrical energy.

**Charge Definition:**

Electric charge is a fundamental property of matter. It can be positive or negative and is measured in **Coulombs (C).**

**Properties of Electric Charge:**

**SI Unit:**Coulomb (C)**Like Charges:**Repel**Unlike Charges:**Attract**Definition:One Coulomb Charge :**1 Coulomb of charge experiences a force of 1 Newton (N) when placed 1 meter away from an equal charge in a vacuum.**One Electron Charge:**A single electron carries a charge of**-1.602 x 10**^{-19}C.

**Electric Potential:**

**Definition:** Electric potential is a measure of the energy required to move a unit charge within an electric field.

**Properties of Electric Potential **

**Scalar Quantity:**It has magnitude but no direction; it's like measuring height.**SI Unit:**Measured in Volts (V),

where, **1 V = 1 Joule per Coulomb (1 J/C).**

**Potential Difference:**

- Potential difference, or voltage (V), is the difference in electric potential between two points in a circuit.
- It signifies the work done in moving one Coulomb of charge between one points another required point.
**P.D**=**V**_{2 }-**V**_{1}

**Electric device wich measure Potential difference (Voltage): Voltmeter**

- A voltmeter is an instrument used to measure voltage (potential difference) between two points in an electrical circuit.

**Why Voltmeter Connected in Parallel?**

- A voltmeter is connected in parallel because it needs to measure potential difference without affecting the circuit's current flow.

**Electricity Types:**

There are two main types: **Static Electricity** and **Electric Current.**

**Static Electricity Definition:**Static electricity is excess electric charge on an object's surface due to friction.

**Examples: After rubbing...**

- Comb and Paper: Comb negatively charged, paper positively charged.
- Balloon and Wall: Balloon negatively charged, wall positively charged.
- Glass Rod and Wool: Glass rod positively charged, wool negatively charged.
- Ebonite Rod and Silk: Ebonite rod negatively charged, silk positively charged.

**Lightning during Thunder:** Static electricity in clouds discharges as lightning due to charge buildup.

**Current Electricity**

**Definition:**Current electricity is the flow of electric charge (usually electrons) through a conductor, creating an electric current.**SI Unit of Current :**The unit of electric current is the Ampere (A), representing the rate of flow of charge.

**Electric device used to measure electric current in circuit: Ammeter**

**Ammeter:** An ammeter is a device used to measure electric current in a circuit. It provides a quantitative measure of the flow of electric charge, typically in amperes (A).

**Why Ammeter connected in series?**

**Low Resistance:**Ammeters have very low internal resistance to minimize their impact on the circuit being measured. This ensures that the current flows primarily through the ammeter, providing an accurate reading..

**Ohm’s Law****:**

- Ohm's Law states that the at
**constant temperature**, current**(I)**flowing through a conductor is**directly proportional**to the voltage**(V)**across it and**inversely proportional**to the resistance**(R)**.

Mathematical representation:

**V ∝ I****V = R I = IR ( R is proportional constant)****R**is called**Resistance**

**Resistance **

**Definition** : Resistance (R) is the property of a material that opposes the flow of electric current.

**SI Unit**: Ohm (Ω)

**Resistors Combinations:**

- Resistors can be combined in
**series**and**parallel**combinations.

**Series Combination in Electric Circuits:**

In a series combination of resistors in an electric circuit, the resistors are connected end to end so that there's only one path for the current to flow.

**Properties**

**Constant Current(I):**In a series arrangement, the same current flows through each resistor. This is because there's only one path for the current to follow, and it remains constant throughout the circuit.**Potential Difference V)Varies:**While the current remains the same, the potential difference (voltage) across each resistor can vary. The voltage drop across each resistor is additive, meaning the total voltage across the series of resistors is the sum of the individual voltage drops.**Voltage in Series:**In a series circuit with resistors R_{1}, R_{2}, and R_{3}, the total voltage (V) is the sum of the individual voltage drops:

**Parallel Combination in Electric Circuits:**

In a parallel combination of resistors in an electric circuit, the resistors are connected side by side, providing multiple paths for the current to flow.

**Properties:**

**Constant Voltage (V):**In a parallel arrangement, each resistor has the same voltage across its terminals. This is because all resistors are connected directly across the voltage source.**Current Varies:**While the voltage across each resistor is constant, the current flowing through each resistor can vary. Each resistor receives a portion of the total current, and the sum of the currents through all resistors equals the total current in the circuit.**Current in Parallel:**In a parallel circuit with resistors R1, R2, and R3, the total current (I) is the sum of the currents through each resistor:

**Why Domestic Wiring in Parallel?**

- Domestic wiring is in parallel to ensure that one device's failure doesn't disrupt the entire circuit. It provides flexibility and safety.

**Differences between Series Combination and Parallel combinations **

**Factors Affecting Resistance:**

Resistance is affected by:

**Length**(L) of the conductor**directly proportional**to**resistance**of conductor**R $∝$ L ........(i)****Cross-sectional area**(A) of the conductor inversely proportional to resistance of conductor.**R $∝$ 1/ A .......(ii)**- The nature of the
**material**. **Temperature**(T) of the conductor.

Mathematical representation: from **(i)** and **(ii)**

$∝$

**R = ρ L/A ** ( **ρ** is constant)

** ρ ** is called **resistivity** of object .

**Resistivity **

**Definition:**Resistivity is a fundamental property of a material and represents the natural resistance of that material when it has a **length of 1 meter (m)** and a cross-sectional **area of 1 m ^{2}**

**SI Unit**: Ohm-meter (Ω·m)

Examples : Resistivity of some matter

**Copper Resistivity:**Copper has a low resistivity, which means it is an excellent conductor of electricity. Its resistivity is approx 1.68 × 10^{-6}Ωm**Nichrome Alloy Resistivity:**Nichrome alloy, commonly used in heating elements, has a higher resistivity compared to copper. Its resistivity is 1.10 × 10^{-6}Ωm**Plastic Resistivity:**Plastic materials have very high resistivity, making them excellent insulators. The resistivity of plastics varies depending on the specific type but is significantly higher than that of conductors

**Electric Power**

**Definition**: Electric power is the rate at which electrical energy is produced, consumed, or transferred.**SI Unit:**Watt (W)

**Electric Power Formulas:**

**Define 1 Watt **

- One watt is equal to one joule of energy per second.

**Commercial and SI Unit of Power:**

- Commercially, power is often measured in kilowatts (kW), while the SI unit remains the watt (W).

**Electric Energy:**

**Definition**: Electric energy is the amount of work done by the flow of electric charge.**Formula**: Electric energy (E) = Power (P) × Time (t)

**Joule’s Law of Heating**

**Joule's Law**states that the heat produced in a resistor is directly proportional to the square of the current**(I)**and resistance**(R)**.**Formula**:**H**=**I**^{2}R t

**Relation between Commercial and SI Unit of Electric Energy:**

**Electric Fuse:**

**Definition**: electric fuse is a protective device that breaks the circuit when the current exceeds a certain value, preventing damage and fire hazards.- Fuses are arranged in
**series**with the circuit and work by melting or breaking when overloaded.

**Short-Circuit **

**Definition:**Short-circuit occurs when two live conductors touch, causing excessive current flow. A short-circuit is an unintended low-resistance connection between two live conductors.**Preventing Methods:**Proper insulation, circuit breakers, and not overloading circuits help prevent short-circuits and overloads.

**Overloading**

**Definition:** Overloading occurs when a circuit carries a current beyond its capacity due to connected devices drawing too much current. This can lead to overheating, insulation damage, fires, or electrical failures. Preventive measures include distributing loads, using circuit breakers, and avoiding connections that collectively draw more current than the circuit can handle.

**Preventing Methods:**Proper insulation, circuit breakers, and not overloading circuits help prevent short-circuits and overloads.

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