Re: Electronics 101 Question .....

Posted by John T on October 25, 2006 at 19:15:46 from (66.244.90.5):

In Reply to: Electronics 101 Question ..... posted by MMB on October 25, 2006 at 15:35:07:

MMB SHORT ANSWER: If there were but one resistor placed across a voltage source at a time, the smaller resistor would dissipate more heat then a larger resistor DUH since the voltage is the same 6 volts but the current (E/R) is greater through the smaller resistor and Power = E x I........................ Got it?????

MMB, LONG ANSWER:

BEFORE we can give a correct answer we need a CORRECT question such as Volts or Amps being supplied, and, of course, if small and large resistors were in series or paralell if you wanted to use both in a single circuit for comparisons. Did you intend a fixed voltage source across the resistors or a fixed current source as you mentioned BOTH????

If you apply a voltage source across
resistor(s) Ohms law tell us the current draw is E/R and the power it will disspate in the form of heat is E x I or I squared x R or E squared/R SIMPLE AS THAT.

So, at the same voltage say 10 volts across two resistors in "paralell" a smaller 5 ohm and a larger 10 ohm, the power dissipated in the form of heat in the smaller 5 ohm resistor is 100/5 = 20 watts, while in the larger 10 ohms the power is 100/10 = 10 watts THE SMALLER RESISTOR DISSIPATES THE MOST POWER IN THE PARALELL COMBINATION.

If the resistors were placed in "series" across a 10 volt source, each resistor receives the same amount of current flowing through it (10/15 = 0.666 amps) but theres a different voltage drop across each individual resistor, the sum of which equals the 10 volt source. There would be 6.666 volts dropped across the larger 10 ohm resistor but only 3.333 dropped across the smaller 5 ohm resistor. In that "series" situation the power dissipated in the smaller 5 ohm resistor would be E x I or 3.333 x 0.666 but in the larger 10 ohm resistor the power dissipated would be the same 0.666 amps x 6.666 volts SO THE LARGER RESISTOR DISSIPATES MORE POWER IN THE SERIES SITUATION.

Hope this helps explain and clarify your question, let us know, best wishes n God Bless

John T

Replies:

• Re: Electronics 101 Question ..... Bob 21:48:02 10/25/06 (1)
  • Re: Electronics 101 Question ..... John T 06:27:09 10/26/06 (0)

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