1
GATE ME 2022 Set 1
Numerical
+1
-0

A flat plate made of cast iron is exposed to a solar flux of 600 W/m2 at an ambient temperature of 25 °C. Assume that the entire solar flux is absorbed by the plate. Cast iron has a low-temperature absorptivity of 0.21. Use Stefan-Boltzmann constant = 5.669 × 10-8 W/m2-K4. Neglect all other modes of heat transfer except radiation. Under the aforementioned conditions, the radiation equilibrium temperature of the plate is __________ °C (round off to the nearest integer).

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2
GATE ME 2017 Set 2
MCQ (Single Correct Answer)
+1
-0.3
The emissive power of a blackbody is $$P.$$ If its absolute temperature is doubled, the emissive power becomes
A
$$2P$$
B
$$4P$$
C
$$8P$$
D
$$16$$$$P$$
3
GATE ME 2016 Set 2
MCQ (Single Correct Answer)
+1
-0.3
Consider the radiation heat exchange inside an annulus between two very long concentric cylinders. The radius of the outer cylinder is $${R_0}$$ and that of the inner cylinder is $${R_i}$$ . The radiation view factor of the outer cylinder onto itself is
A
$$1 - \sqrt {{{{R_i}} \over {{R_0}}}} $$
B
$$\sqrt {1 - {{{R_i}} \over {{R_0}}}} $$
C
$$1 - {\left( {{{{R_i}} \over {{R_0}}}} \right)^{1/3}}$$
D
$$1 - {{{R_i}} \over {{R_0}}}$$
4
GATE ME 2012
MCQ (Single Correct Answer)
+1
-0.3
For an opaque surface, the absorptivity $$\left( \alpha \right),$$ transmissivity $$\left( \tau \right)$$ and reflectivity $$\left( \rho \right)$$ are related by the equation:
A
$$\alpha + \rho = \tau $$
B
$$\rho + \alpha + \tau = 0$$
C
$$\alpha + \rho = 1$$
D
$$\alpha + \rho = 0$$
GATE ME Subjects
Turbo Machinery
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