Resistance plays a major role in our daily life when we use electrical and electronic devices like fan, mixer, iron box, heater, soldering iron, smartphone, laptop etc... Are all resistance the same?
Have you heard about electrcial resistance? What is it exactly?
Resistance is the property of a conducting wire to obstruct or resist the flow of current. It depends upon the length of the conductor.
Resistance is directly proportional to the length, i.e., iof length increases, resistance increases.
Resistance is inversely proportional to the area of the cross-section. If the thickness of the conductor increases, resistance decreases.
Therefor, thick wires will allow more electric current to flow through them than thin wires. So, a thin wire is said to have more resistance.
Resistance also depends upon the material with which the conductor is made and the temperature of the conductor.
Generally, resistance resists the flow of current in the circuit. It also transforms electrical energy to heat or light.
Electrical Conductance
Electrical conductance is the reciprocal of electrical resistance. Electrical conductance means how well a material allows electric current to flow through it.
Ohm & mho
ohm [Ω] is the unit of resistance. It is named after the German physicist George Simon Ohm.
mho is the SI unit of electrical conductance.
Ohm and Resistance
It was George Simon Ohm who put forward a law known as Ohm's law. According to Ohm's law, when the temperature remains same, the current flowing through a conductor will be directly proportional to the potential difference between its ends.
V=IR
When V is voltage, I is current and R is the resistance
I=V/R, R=V/I
Unit of resistance :- ohm [Ω]
Unit of voltage :- Volt [V]
Unit of electric current :- Ampere [A]
Alessandro Volta and Voltage
The word 'voltage' comes from the famous Italian physicist, Alessandro Volta who invented the electric battery.
Voltage, potential difference, or electomotive force can be explained in a simple way. We can say that it is the pressure that pushes electricity. Or that it is the pressure which pushes electrons through a conducting loop.
Unit of voltage is Volt[V]
Series and Parallel
When we connects two resistors (R1, R2) in series, effective resistance increases. As a result voltage decreases while current remains the same for both resistors. So Effective Resistance, R = R1 + R2
When resistors are connected in parallel, the voltage will be equally distributed. As a result effective resistance decreases but the current will be different.
Effective Ressitance, R=R1R2/(R1+R2)
