Factors affecting The Resistance : Resistivity

EMF (Electromotive Force) vs Potential Difference


1. EMF: The energy per unit charge provided by a power source (like a battery) to drive current through a circuit.

2. Potential Difference (Voltage): The difference in electric potential between two points in a circuit, causing current to flow.


Key differences:


1. Source vs Effect: EMF is the source of energy, while potential difference is the effect of that energy in the circuit.

2. Internal vs External: EMF is internal to the power source, while potential difference is measured across external circuit components.


Relationship:


1. EMF drives current: EMF creates a potential difference, which drives current through the circuit.


Want to explore more about electric circuits?

[7:56 AM, 7/25/2025] Ajit Kumar: Ohm`s law : Resistance

Ohm's Law


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


Formula:


V = I × R


Key Points:


1. Voltage (V): The potential difference across the conductor.

2. Current (I): The flow of electric charge through the conductor.

3. Resistance (R): The opposition to the flow of electric charge.


Applications:


1. Circuit design: Ohm's Law helps design and analyze electric circuits.

2. Component selection: It aids in selecting components with suitable resistance values.


Examples:


1. Resistors: Used to control current flow in circuits.

2. Wiring: Ohm's Law helps determine the required wire gauge for safe current flow.


Want to explore more about Ohm's Law or circuit analysis?

[8:00 AM, 7/25/2025] Ajit Kumar: Factors affecting The Resistance : Resistivity

Factors Affecting Resistance


The resistance of a conductor depends on several factors:


1. Material: Different materials have varying resistivities (e.g., copper is a good conductor, while rubber is an insulator).

2. Length: Longer conductors have higher resistance.

3. Cross-sectional Area: Thicker conductors have lower resistance.

4. Temperature: Resistance increases with temperature for most materials.


Resistivity (ρ)


Resistivity is a measure of a material's inherent ability to resist electric current. It's a property of the material itself, independent of its shape or size.


Formula:


R = ρ × (L/A)


Where:

R = Resistance

ρ = Resistivity

L = Length

A = Cross-sectional Area


Examples:


1. Copper wiring: Used in electrical systems due to its low resistivity.

2. Insulators: Materials like rubber or glass have high resistivity, making them suitable for insulation.

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