Resistance

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iragarcia24

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Doing some studying and need some help.

Question: 2 resistors with the resistance of 5 ohms and 7 ohms are connected in series across a 60 volt source. The power absorbed in the 5 ohm is ____ watts?
The answer is 125 watts I'm just not understanding how they got the answer, someone please explain.


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iragarcia24 said:
Doing some studying and need some help.

Question: 2 resistors with the resistance of 5 ohms and 7 ohms are connected in series across a 60 volt source. The power absorbed in the 5 ohm is ____ watts?
The answer is 125 watts I'm just not understanding how they got the answer, someone please explain.


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Power=I2R. R=5+7 or 12 ohm. Current in circuit equals E/R. 60/12=5 amp. Power dissipated in 5 ohm resistor =52x5=125 watts.
Hope this makes it clearer.
 
Total resistance is 12 ohms. P = V*I. V = I*R. Using these equations you'll find total power of 300 watts. The 5 ohm resistor receives 5/12 of this total power. The 7 ohm resistor receives 7/12 of this total power.
 
resistance

resistance

Watts are the same .voltage is not 5 ohm resistor = 25 volts drop 7 ohm =35 volts drop for a total of 60 volts.
 
GoldDigger said:
I think you mean current is the same but voltage is not.

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Agree - he meant current is the same due to series configuration, not watts. As he pointed out, there is different voltage across each resistor. With constant current, the watts are different by P = V*I
 
domnic said:
No I meant watts are the same.
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In a series circuit, current is the same through each component in series due to continuity of charge flow. No net charge builds up at any component, and no charges are created or destroyed, so all current entering a point must equal the current leaving that point. Voltage is divided among the resistors, proportional to each resistance, and adds up to the total source voltage. The Watts are not necessarily the same for each resistor, as they will be proportional to each resistance per Watts=Amps^2*Ohms.
 
resistance

resistance

publicgood said:
Agree - he meant current is the same due to series configuration, not watts. As he pointed out, there is different voltage across each resistor. With constant current, the watts are different by P = V*I
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How are the watts different ? 300 watts pas trough r 5 and r 7.
 
domnic said:
How are the watts different ? 300 watts pas trough r 5 and r 7.
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The energy travels in the electromagnetic field surrounding the circuit, not in the resistors (or the wire for that matter). Also, energy travels along the circuit, not watts. Watts is a measure of how fast the energy is exchanged/converted/dissipated/etc.

The fields change at the resistor and energy leaves the fields and is dissipated (at the rate of 125W for the 5 ohm resistor).
 
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