Now we will look at a case where heat energy is continuously being added to a sy

Question

Now we will look at a case where heat energy is continuously being added to a system, which, of course, causes the system's temperature to continuously rise. Suppose you are designing an electronic circuit element made of 23 mg of silicon. The electric current through it adds energy at the rate of 7.4 mW = 7.4 Times 10 -3 J/s. If your design doesn't allow any heat transfer out of the element, at what rate does its temperature increase? The specific heat of silicon is 705 J/(kg . K).REFLECT At this rate of temperature increase (27 K every minute), the circuit element would quickly self-destruct. Heat transfer is an important design consideration in electronic circuit elements. Suppose you need your silicon circuit element to run continuously for 3 minutes before it shuts off long enough to cool back down to its initial temperature. If the circuit element can withstand a temperature change of 5.6 degreeC without being damaged, what is the maximum rate at which energy can be added to the circuit element? Express your answer in joules per second to two significant figures.

Explanation / Answer

Now,

dT = 5.6 deg C

m = 23 mg = 23*10^-6 kg

C = 705 J/kg.C

time taken t = 3 min = 3*60 = 180 s

So, rate of heat transfer,

P = m*C*dT/t

= 23*10^-6*705*5.6/(180)

= 5.04*10^-4 J/s

Related Questions

Navigate

• Browse (All)
• Browse N
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.