MCQ
A black body at a temperature of ${227^o}C$ radiates heat energy at the rate of $5 cal/cm^2-sec$. At a temperature of ${727^o}C$, the rate of heat radiated per unit area in $cal/cm^2$ will be
- ✓$80$
- B$160$
- C$250$
- D$500$
✓
Answer
Correct option: A.
$80$
a
(a) $\frac{{{E_2}}}{{{E_1}}} = {\left( {\frac{{{T_2}}}{{{T_1}}}} \right)^4}$$ = \left( {\frac{{273 + 727}}{{237 + 227}}} \right) = \frac{{{{(1000)}^4}}}{{{{(500)}^4}}} = 16 \Rightarrow {E_2} = 80$
(a) $\frac{{{E_2}}}{{{E_1}}} = {\left( {\frac{{{T_2}}}{{{T_1}}}} \right)^4}$$ = \left( {\frac{{273 + 727}}{{237 + 227}}} \right) = \frac{{{{(1000)}^4}}}{{{{(500)}^4}}} = 16 \Rightarrow {E_2} = 80$
Need a full question paper?
Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.
Explore more
Similar questions
A pendulum suspended from the ceiling of a train has a period $T$ when the train is at rest. When the train travels same distance per unit time, the period of oscillation is
→What is the restoring force proportional to in simple harmonic motion?
FIgure shows a sphere of mass $500\ g$ moving in a steady flow of air in the $x- $ direction. The air-stream exerts an essentially constant force of $0.9\ N$ on the sphere in the $x-$ direction. If at $t = 0$ the sphere is moving a s shown in the figure, determine the time required for the sphere to cross the $y-$ axis again ........ $\sec$
→If $I_1$ is the moment of inertia of a thin rod about an axis perpendicular to its length and passing through its centre of mass, and $I_2$ is the moment of inertia of the ring formed by bending the rod, then
→A stone of mass $m$, tied to a string is being whirled in a vertical circle with a uniform speed. The tension in the string is
→When a metal wire is stretched by a load, the fractional change in its volume $\frac{\triangle\text{V}}{\text{V}}$ is proportional to.
→The intensity ratio of two waves is $1 : 16$. The ratio of their amplitudes is
→A projectile is thrown with an initial velocity of $(a \hat{ i }+b \hat{ j }) ms ^{-1}$. If the range of the projectile is twice the maximum height reached by it, then
→$250\,gm$ of water and an equal volume of alcohol of mass $200\,gm$ are placed successively in the same calorimeter and cools from $60^{\circ}\,C$ to $55^{\circ}\,C$ in $130\,sec$ and $67 sec$ respectively. If the water equivalent of the calorimeter is $10\,gm$. , then the specific heat of alcohol in cal/gm $cal / gm ^{\circ}\,C$ is
→A projectile is thrown with a velocity of $50\,\, ms^{^{-1}}$ at an angle of $53^o$ with the horizontal Determine the instants at which the projectile is at the same height
→