A spherical ball $A$ of surface area $10 {cm}^{2}$ is kept at the centre of a hollow spherical shell of area $20 {cm}^{2}$ . Surface of $A$ and inner surface of $B$ behave as black bodies. Both $A$ and $B$ are at $300 K$ . Find the radiation energy emitted per second by ball $A$ ?

0.36 W

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0.46 W

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1.76 W

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1.44 W

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Solution

The correct option is B $0.46 W$

Given that, $(Area)_{B} = 2 (Area)_{A}$
Outer surface of $A$ and inner surface of $B$ are black bodies. [i.e $a = 1, e = 1$ ]

Radiation emitted by body $A$
${(\frac{d Q}{d t})}_{A} = e σ A T_{A}^{4}$
$= 1 \times (5.67 \times 10^{- 8}) \times (10 \times 10^{- 4}) \times (300)^{4} J/s$
$= 0.46 W$
Thus, option (b) is the correct answer.

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A spherical ball A of surface area 10 cm2 is kept at the centre of a hollow spherical shell of area 20 cm2. Surface of A and inner surface of B behave as black bodies. Both A and B are at 300 K. Find the radiation energy emitted per second by ball A ?

The correct option is B 0.46 W Given that, (Area)B=2(Area)A Outer surface of A and inner surface of B are black bodies. [i.e a=1, e=1] Radiation emitted by body A (dQdt)A=eσAT4A =1×(5.67×10−8)×(10×10−4)×(300)4 J/s =0.46 W Thus, option (b) is the correct answer.

A spherical ball $A$ of surface area $10 {cm}^{2}$ is kept at the centre of a hollow spherical shell of area $20 {cm}^{2}$ . Surface of $A$ and inner surface of $B$ behave as black bodies. Both $A$ and $B$ are at $300 K$ . Find the radiation energy emitted per second by ball $A$ ?