# Resistor Tutorial Summary

We can summarize this resistor tutorial section and what we have learnt as follows:

• The job of a Resistor is to limit the current flowing through an electrical circuit.
• Resistance is measured in Ohm’s and is given the symbol Ω
• Carbon, Film and Wirewound are all types of resistors.
• Resistor colour codes are used to identify the resistance and tolerance rating of small resistors.
• The BS1852 Standard uses letters and is used to identify large size resistors.
• Tolerance is the percentage measure of the accuracy of a resistor from its preferred value with the E6 (20%), E12 (10%), E24 (5%) and E96 (1%) series of tolerance values available.

## Series Resistor Tutorial

• Resistors that are daisy chained together in a single line are said to be connected in SERIES.
• Series connected resistors have a common Current flowing through them.
• Itotal = I1 = I2 = I3 …. etc

• The total circuit resistance of series resistors is equal to:
• Rtotal = R1 + R2 + R3 + ….. Rn etc.
• Total circuit voltage is equal to the sum of all the individual voltage drops.
• Vtotal = V1 + V2 + V3 …. etc

• The total resistance of a series connected circuit will always be greater than the highest value resistor.

## Parallel Resistor Tutorial

• Resistors that have both of their respective terminals connected to each terminal of another resistor or resistors are said to be connected in PARALLEL.
• Parallel resistors have a common Voltage across them.
• VS = V1 = V2 = V3 …. etc

• Total resistance of a parallel circuit is equal to:
• Total circuit current flow is equal to the sum of all the individual branch currents added together.
• Itotal = I1 + I2 + I3 …. etc

• The total resistance of a parallel circuit will always be less than the value of the smallest resistor.

## Resistor Power Rating

• The larger the power rating, the greater the physical size of the resistor to dissipate the heat.
• All resistors have a maximum power rating and if exceeded will result in the resistor overheating and becoming damaged.
• Standard resistor power rating sizes are 1/8 W, 1/4 W, 1/2 W, 1 W, and 2 W.
• Low ohmic value power resistors are generally used for current sensing or power supply applications.
• The power rating of resistors can be calculated using the formula:
• In AC Circuits the voltage and current flowing in a pure resistor are always “in-phase” producing 0o phase shift..
• When used in AC Circuits the AC impedance of a resistor is equal to its DC Resistance.
• The AC circuit impedance for resistors is given the symbol Z.

• H
Harry

Good Tutorial.

find the overall capacitance &individual voltage drops across two capacitor each with capacitance 470nF,&1microF respectively in series when they are connected to AC voltage.

calculate the equivalent capacitance in series and parallel when three capacitors having capacitance 31F ,35F, 36F respectively.

• P
Pulkit

Can someone please tell me that how does a rheostat control the amount of current in a circuit?

• w
woodywood picker

i learn a lot of things in this tutorial… thanks guys….

• e

this page is of great help to me,.now, i can study in my own time w/the help of this page even w/o going to electronics/vocational school….thanks a lot…

• s
sudheer

i can design one circuit but how much of resistor value used i don’t no please tell me

• i
iddriss

u wil only one resister

• Wayne Storr

R (ohms) = Voltage/Current, (R = V/I). If you know the voltage across the resistor and the current expected to flow through it you can calculate the required resistance.

• k
khalid

Today in my tutorial i got resistor basics very well and i want to review my knowledge of electronics as i worked for about 20 years as electronics technician and in coming days going to search another job as electronics technician.

• P
Philip Malmstedt

I want to study about electronics. I want to purse my goal to become a technician in the future. I am a hearing-impared person and am 48 years old. I have not completely finished this courses in the colleges and not getting it successfully. I want to learn what the electronics work.

• Wayne Storr

Hello Philip, Everything you need to learn Electronics is right here. Good look with your studies.

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