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Current through resistor, with heat. What happens to the current?

by rcmango
Tags: current, heat, resistor
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rcmango
#1
Aug17-11, 05:38 AM
P: 234
1. The problem statement, all variables and given/known data

Suppose a current of 1 A is flowing through a resistor. If this makes the resistor heat up, will the current through the resistor increase, decrease, or remain constant? Assume the voltage applied to the resistor is constant.

2. Relevant equations



3. The attempt at a solution

Please help me with this, i'm not sure, but I believe the current will decrease slightly because of the heat dissipated?
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PeterO
#2
Aug17-11, 06:19 AM
HW Helper
P: 2,318
Quote Quote by rcmango View Post
1. The problem statement, all variables and given/known data

Suppose a current of 1 A is flowing through a resistor. If this makes the resistor heat up, will the current through the resistor increase, decrease, or remain constant? Assume the voltage applied to the resistor is constant.

2. Relevant equations



3. The attempt at a solution

Please help me with this, i'm not sure, but I believe the current will decrease slightly because of the heat dissipated?
The resistance of many electrical components changes with temperature. Certainly the resistance of a wire increases when it gets hotter, so if the resistor is actually made up of a length of wire you can expect that change in resistance - with an effect on the current I am sure you can predict.
rcmango
#3
Aug17-11, 07:48 PM
P: 234
Okay, so as the wire heats up the resistance of the wire increases, this causes the current to decrease. Is that correct?

PeterO
#4
Aug17-11, 08:32 PM
HW Helper
P: 2,318
Current through resistor, with heat. What happens to the current?

Quote Quote by rcmango View Post
Okay, so as the wire heats up the resistance of the wire increases, this causes the current to decrease. Is that correct?
That sounds good.

EDIT: provided the resistor is made using wire.
phinds
#5
Aug17-11, 10:01 PM
PF Gold
phinds's Avatar
P: 6,320
The current decrease is NOT because of the heat dissipated. For an ideal resistor that does not change resistance even if it heats up, the current doesn't change.


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