1
AIPMT 2007
+4
-1
Assuming the sun to have a spherical outer surface of radius r, radiating like a black body at temperature toC, the power received by a unit surface, (normal to the incident rays) at a distance R from the centre of the sun is
where $$\sigma$$ is the Stefan's constant.
A
$${{{r^2}\sigma {{\left( {t + 273} \right)}^4}} \over {4\pi {R^2}}}$$
B
$${{16{\pi ^2}{r^2}\sigma {t^4}} \over {{R^2}}}$$
C
$${{{r^2}\sigma {{\left( {t + 273} \right)}^4}} \over {{R^2}}}$$
D
$${{4\pi {r^2}\sigma {t^4}} \over {{R^2}}}$$
2
AIPMT 2007
+4
-1
A black body is at 727oC. It emits energy at a rate which is proportional to
A
(1000)4
B
(1000)2
C
(727)4
D
(727)2
3
AIPMT 2006
+4
-1
A black body at 1227oC emits radiations with maximum intensity at a wavelength of 5000 $$\mathop A\limits^ \circ$$. If the temperature of the body is increased by 1000oC, the maximum intensity will be observed at
A
3000 $$\mathop A\limits^ \circ$$
B
4000$$\mathop A\limits^ \circ$$
C
5000$$\mathop A\limits^ \circ$$
D
6000$$\mathop A\limits^ \circ$$
4
AIPMT 2005
+4
-1
Which of the following rods, (given radius r and length $$l$$) each made of the same material and whose ends are maintained at the same temperature will conduct most heat ?
A
r = r0, $$l$$ = $$l$$0
B
r = 2r0, $$l$$ = $$l$$0
C
r = r0, $$l$$ = 2$$l$$0
D
r = 2r0, $$l$$ = 2$$l$$0
EXAM MAP
Medical
NEET