Answer:
The answer is below
Explanation:
Given that:
ρ = 800 kg/m3, c = 600 J/kg-K, k = 40 W/m-K, Initial temperature = Ti = 1150,
Environment temperature = T = 450 K, Final temperature = T∞ = 325 K
Diameter = 10 mm = 0.01 m, A = 6
The estimated time for cooling process (t) is given as:
The estimated cooling time is 589 s
Answer:
a) I_LED= 1/6 A b) Vf= 2.5V
Explanation:
Consider circuit in the attachment.
a) We will simplify current source in paraller with resistor to a voltage source in series with a resistor(see attachment 2)
Solving the circuit in attachment 2 using mesh analysis
-9+2I1+4(I1-I2)-4+2I1=0
8I1 - 4I2= 13 ............... eq 1
4+4(I2-I1)+ I2 + 2=0
4I1- 5I2 = 6 ............ eq 2
I1= 41/24 ; I2 = 1/6; I2= I_LED
b) Solving the circuit in attachment 2 again, this time I2=0
8I1 - 4I2= 13
8I1- 4(0)=13
I1= 13/8
Vf= 4(I1- I2) -4
I2=I_LED=0
Vf= 2.5 V
