I\'m having some trouble thinking about a resistance problem. I want to figure o

Question

I'm having some trouble thinking about a resistance problem. I want to figure out how long it takes, after current starts, for a resistor to reach a power load of 1W. The resistor is a 1-g resistor. The current is 30mA. I was thinking that I could take the resistance value...and knowing that that an Ohm is also J/(s*A^2)...use the Amps to reduce the value down to the amount of Joules. Then, use the value of the Joules to figure out the time since 1 W = 1 J/s.

This sounds like its not the proper way to think about this problem. I feel that it should be a lot simpler than that. Fro this I'm suppose to figure out the temperature and I'm curious if I should be working with a temperature equation such as R_T=R_0(1+a deltaT).

I'm pretty confused and would appreciate any help.

Explanation / Answer

as time increases,resistance value increases due to increase in tempearature.

now increase in temeprature is governed by newtons law

dT/dt=K*A*(T-T0)

where T0=ambient temperature

so solve for T from here.

then put into the value of resistance as R*(1+a*deltaT)

then power=V^2/R

dont use I^2*R as I will change when R changes.

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