Energy, Power and Resistance The study of energy , power , and resistance is fundamental in understanding electrical circuits and their behavior. This topic enc...
The study of energy, power, and resistance is fundamental in understanding electrical circuits and their behavior. This topic encompasses key concepts such as Ohm's law, factors affecting resistance, and calculations related to electrical energy and power.
Ohm's law states that the current I flowing through a conductor between two points is directly proportional to the voltage V across the two points and inversely proportional to the resistance R of the conductor. This relationship can be expressed with the formula:
V = I × R
The resistance of a conductor is influenced by several factors:
Resistivity is a material property that quantifies how strongly a given material opposes the flow of electric current. It is denoted by the symbol ρ and is defined as:
ρ = R × (A / L)
Where R is the resistance, A is the cross-sectional area, and L is the length of the conductor.
The electrical energy E consumed in a circuit can be calculated using the formula:
E = P × t
Where P is the power and t is the time in seconds. Power P can also be expressed in terms of voltage and current:
P = V × I
Efficiency is a measure of how much input energy is converted into useful output energy. It can be calculated using the formula:
Efficiency (%) = (Useful Energy Output / Total Energy Input) × 100
Understanding the relationships between energy, power, and resistance is crucial for analyzing electrical circuits. Mastery of these concepts enables students to solve complex problems and apply their knowledge in practical situations.
Problem: A resistor of resistance 10 ohms has a current of 2 A flowing through it. Calculate the voltage across the resistor and the power dissipated.
Solution: