Question

Two metal cubes with 3 cm edges of copper and aluminium are arranged

Answer 1

Answer :

Correction in the question : 2 metal cube's with 3 centimeter edges of Aluminium and copper are assembled as shown in figure. Then find the total thermal current from one reservior to the other. The thermal conductivity of of Aluminum is 237 W/m-K and Copper is 401 W/m-K.

SOLUTION :

Let the thermal resistance of Al cube be R1.

Let the thermal resistance of Cu cube be R2.

Applying the formula of thermal resistance,

R = l/KA

Thermal resistance of Al will be

R1 = l/KA

R1 = 3 × (10^-2)/237 × (3 × 10^-2)^2

R1 = 0.14 K/W

Calculation of thermal resistance of Cu

R2 = l/KA

R2 = 3 × (10^-2)/401 × (3 × 10^-2)^2

R2 = 0.08 K/W

From the figure we can clearly see that the given two resistances are connected in parallel way, so their equivalent resistance will be -

R = (R1R2/R1 + R2)

R = 0.14 × 0.08/0.14 + 0.08

R = 0.05 K/W

the total thermal current from one reservior to the other = Thermal Difference/Thermal Resistance

= 100 -20/0.05

= 1.6 × 10^3 W

Hence, the required answer is 1.6 × 10^3

Answer 2

Answer:

240 watt

i(thermal current)=T(higher) - T(lower) /resistance

As they are parallely connected so resistance is given by

R = L/KA

here K is the thermal conductivity in parallel connection K is given by

K (equivalent) = k1+ k2

so, i = 240