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What it does? Answered

HI, i have a circuit  in the image above this is a simple led circuit but i found a resistor between positive and negetive terminal  the resistor's value is 15 kilo ohms but i don't know what it does in this circuit can anybody tell me ( Elaborate! ).
Samad Haque



Best Answer 5 years ago

The resistor should be in SERIES with the LED... not in parallel. Also, are you sure the resistor is 15K? That is very high resistance. 1.5K is more likely. A very high value indicates the LED is connected to a VERY high voltage in order to get 20milliamps or so through the LED. The color code for 15k is BROWN-GREEN-ORANGE.... and the code for 1.5K is BROWN-GREEN-RED. If the resistor is as described in your question, it makes no sense to me.

Does the resistor reduce the voltage of the whole circuit in this case?

No it will not. His diagram shows all 3 components connected in PARALLEL. Therefore the battery is delivering full voltage and full amperes to both components, the resistor and the LED. In order for the resistor to lower the voltage to the LED, the 3 components must be connected in SERIES, .................... like this:

Thanks for answering sir,
But i checked a lot of time and the colouring is as same as 15k that's brown,green,orange. i found this circuit in a fly killer shock racket i has an emergency led light for genral use the light's circuit is exactly as same as i have given but it also had a polarised resistor! of 10 volts and 470uf .i will recheck very properly and tell you that!

The component you call a "polarized resistor" is actually an "electrolytic capacitor". Capacitors are marked in units called "Farads". One Farad is a
very large item, so capacitors are labeled in Micro-farads (uF) which is a smaller number. A capacitor is similar to a small battery that can hold an electric charge for a few seconds. It is made out of 2 pieces of metal foil separated by an insulator such as plastic. Your questions indicate that you are just beginning to learn electronics. Thats ok to be new. You might want to read some instructables on "beginning electronics" to advance your knowledge. There are LOTS of instructables that would help beginners here. Just do a search for "electronics beginner" to see what is available.

Sir ,
i am kind to inform you that i am only 15 i begin electronics fro the age of 9 ( just make some light bulbs and moving motors ) . then my intrest diverted to Web Developer then i joinned back electronics this year . but i want to tell you " polarized resistor " is an typing error my actual meaning is polarized capacitor and i also know basic electronics! but not upto your level sir!