Saturday, 7 January 2012

Resistance

Discuss briefly about the resistance.
How it will vary by varying its connections? describe.

6 comments:

Electronics Club for Engineers said...

Resistance (R) is defined as the ratio of the voltage (V) across a conductor to the current (I) flowing through it. Mathematically, R = V/I, which is also known as Ohm's Law.

The unit of measurement for resistance is the 'ohm', Ω, which is defined as volt/ampere.

A component fabricated to exhibit nothing but a certain resistance (ideally) is known as a resistor.

Electronics Club for Engineers said...

The higher the resistance, the greater is the voltage required to attain a given amount of current flow. Resistance is therefore, as its name implies, a measure of the ability of a conductor to resist the flow of current.

Electronics Club for Engineers said...

Resistance is an extrinsic property, i.e., its value is affected by characteristics that are not inherent to the conductor, such as the conductor's dimensions.

The inherent characteristic of a material that defines its ability to resist the flow of current is known as its 'resistivity', ρ.

The resistance R is related to the resistivity ρ by the equation: R=ρL/A, where L is the length of the conductor and A is its cross-sectional area.

Electronics Club for Engineers said...

Resistors may be connected to each other to form new values of resistance. They may be connected in series or in parallel.

Electronics Club for Engineers said...

When two or more resistances are connected in series, the currents through each of them are equal. However, the corresponding voltage developed across each of them differs in accordance with Ohm's Law. Thus, for a given circuit consisting of N resistors connected in series and excited by a voltage V, I = V1/R1 = V2/R2 = ... = VN/RN, where I is the current flowing through the circuit and Vi is the corresponding voltage developed across every individual resistance Ri, such that V = V1 + V2 +... + VN.

Electronics Club for Engineers said...

When two or more resistances are connected in parallel, the voltages across each of them are equal. However, the corresponding current flowing through each of them differs in accordance with Ohm's Law. Thus, for a given circuit consisting of N resistors connected in parallel and excited by a voltage V, V = I1R1 = I2R2 = ... = IN/RN, where Ii is the corresponding current flowing through every individual resistance Ri.