hi,

1.how do we calculate the power rating for series connected resistors?

**-Determine the total resistance, then determine the current draw. Current will be the same through ALL items in series.**

-Use the current through the resistor, and the resistor value to determine power.

-This will ONLY apply to items connected in series, and will NOT apply to parallel components.

2.how do we calculate the power rating for parallel connected resistors?

**-Find the voltage drop across each resistor, which will let you directly use Voltage, and Resistance to determine Power (Using Algebra on the two formulas below) **

-Or you can calculate current first with voltage and resistance, then power.

-This will apply to series or parallel components as long as you can determine the voltage *across* the component you are calculating.

3.which type of connection is mostly preferable ?

**-This depends entirely on preference and use. There is no answer here.**

thanks regards...

Formulas:

V = IR (Voltage = Current * Resistance)

P = IV (Power = Current * Voltage)

Adding series resistors to get total resistance:

Rt = R1 + R2 + R3 + ... + Rn

Adding parallel resistors to get total resistance:

1/Rt = ( 1/R1 + 1/R2 + 1/R3 + ... + 1/Rn )

Please remember that the voltage across a single component may not be the same as the voltage supplied to the entire circuit.

These formulas assume you can determine the voltage across each resistor individually to correctly calculate power rating.

All example assume simple series or parallel circuits where there is two or more items connected in series or parallel and not any combination of both!

*Harald is speedy