Why doesn't a resistor burn up when its power rating is exceeded?

AI Thread Summary
The discussion revolves around a 10-ohm resistor rated at 1W, which was subjected to a power of 10W without burning up. The user questions why the resistor did not fail despite exceeding its power rating. It is suggested that the presence of water in the experiment absorbed excess heat, preventing the resistor from overheating. The cooling effect of water is noted as a crucial factor in managing the resistor's temperature. Overall, the resistor's ability to dissipate heat effectively in this setup explains its survival despite the power excess.
sarahjt1
Messages
9
Reaction score
0

Homework Statement



The heating resistor is rated at 10ohms and 1W. By how much was its power exceeded? Why didn't the resistor burn up?

This is a question taken from an Electrical Equivalent of Heat lab assignment... here is a link to the exact same lab we did...

http://www.kbcc.cuny.edu/academicDepartments/PHYSCI/physics_12_14/pdf/Experiment4_EEquivalent_Heat.pdf

Homework Equations



P=V^2/R where V=10ohms and R=10ohms

The Attempt at a Solution



P=10W but the resistors rating was 1W and I don't really know why it didn't burn up. My only guess is that some of the power was lost due to the water absorbing some of the energy given off by the resistor?

Help! :confused:
 
Last edited by a moderator:
Physics news on Phys.org
sarahjt1 said:
P=10W but the resistors rating was 1W and I don't really know why it didn't burn up. My only guess is that some of the power was lost due to the water absorbing some of the energy given off by the resistor?

Your guess is correct. The ratings of power resistors do not take into account cooling them with water.
 

Thread 'Errors and significant figures'

I multiplied the values first without the error limit. Got 19.38. rounded it off to 2 significant figures since the given data has 2 significant figures. So = 19. For error I used the above formula. It comes out about 1.48. Now my question is. Should I write the answer as 19±1.5 (rounding 1.48 to 2 significant figures) OR should I write it as 19±1. So in short, should the error have same number of significant figures as the mean value or should it have the same number of decimal places as...
View full post »
Thread 'A cylinder connected to a hanging mass'

Thread 'A cylinder connected to a hanging mass'

Let's declare that for the cylinder, mass = M = 10 kg Radius = R = 4 m For the wall and the floor, Friction coeff = ##\mu## = 0.5 For the hanging mass, mass = m = 11 kg First, we divide the force according to their respective plane (x and y thing, correct me if I'm wrong) and according to which, cylinder or the hanging mass, they're working on. Force on the hanging mass $$mg - T = ma$$ Force(Cylinder) on y $$N_f + f_w - Mg = 0$$ Force(Cylinder) on x $$T + f_f - N_w = Ma$$ There's also...
View full post »

Similar threads

RC Circuit - Rate energy is dissipated in the resistor
Replies
4
Views
2K
Joule heating effect - qualitative explanation
Replies
8
Views
2K
Power Resistor Immersed In Water
Replies
4
Views
3K
Solving a Series Circuit with Unequal Resistor Powers
Replies
12
Views
1K
Power of resistors in parallel vs series circuit
Replies
7
Views
3K
Total rate at which electrical energy is dissipated by resistors
Replies
6
Views
9K
How Do You Determine the Load Resistor Value for Maximum Power Dissipation?
Replies
25
Views
3K
How Does Adding a Resistor Affect Power Dissipation in a Parallel Circuit?
Replies
9
Views
3K
Calculating power of one of two resistors
Replies
1
Views
2K
Power dissipated by a resistor in a circuit
Replies
2
Views
2K

Hot Threads

Recent Insights

Back
Top