Physics-
General
Easy
Question
The spectral emissive power 
for a body at temperature T1 is plotted against the wavelength and area under the curve is found to be A. At a different temperature T2 the area is found to be 9A. Then 
=
- 3
- 1/3
The correct answer is:
Related Questions to study
physics-
A hollow sphere of inner radius R and outer radius 2R is made of a material of thermal conductivity K. It is surrounded by another hollow sphere of inner radius 2R and outer radius 3R made of same material of thermal conductivity K. The inside of smaller sphere is maintained at 0°C and the outside of bigger sphere at 100°C. The system is in steady state. The temperature of the interface will be :
A hollow sphere of inner radius R and outer radius 2R is made of a material of thermal conductivity K. It is surrounded by another hollow sphere of inner radius 2R and outer radius 3R made of same material of thermal conductivity K. The inside of smaller sphere is maintained at 0°C and the outside of bigger sphere at 100°C. The system is in steady state. The temperature of the interface will be :
physics-General
physics-
A metallic rod of cross-sectional area 9.0 cm2 and length 0.54 m, with the surface insulated to prevent heat loss, has one end immersed in boiling water and the other in ice-water mixture. The heat conducted through the rod melts the ice at the rate of 1 gm for every 33 sec. The thermal conductivity of the rod is
A metallic rod of cross-sectional area 9.0 cm2 and length 0.54 m, with the surface insulated to prevent heat loss, has one end immersed in boiling water and the other in ice-water mixture. The heat conducted through the rod melts the ice at the rate of 1 gm for every 33 sec. The thermal conductivity of the rod is
physics-General
physics-
Six identical conducting rods are joined as shown in figure. Points A and D are maintained at temperature of 200°C and 20°C respectively. The temperature of junction B will be:
Six identical conducting rods are joined as shown in figure. Points A and D are maintained at temperature of 200°C and 20°C respectively. The temperature of junction B will be:
physics-General
physics-
Twelve conducting rods form the riders of a uniform cube of side 'l'. If in steady state, B and H ends of the rod are at 100°C and 0°C. Find the temperature of the junction 'A'.
Twelve conducting rods form the riders of a uniform cube of side 'l'. If in steady state, B and H ends of the rod are at 100°C and 0°C. Find the temperature of the junction 'A'.
physics-General
physics-
Three rods made of the same material and having same cross-sectional area but different lengths 10cm, 20 cm and 30 cm are joined as shown. The temperature of the joint is:
Three rods made of the same material and having same cross-sectional area but different lengths 10cm, 20 cm and 30 cm are joined as shown. The temperature of the joint is:
physics-General
physics-
A ring consisting of two parts ADB and ACB of same conductivity k carries an amount of heat H. The ADB part is now replaced with another metal keeping the temperatures T1 and T2 constant. The heat carried increases to 2H. What should be the conductivity of the new ADB part? Given 
= 3:
A ring consisting of two parts ADB and ACB of same conductivity k carries an amount of heat H. The ADB part is now replaced with another metal keeping the temperatures T1 and T2 constant. The heat carried increases to 2H. What should be the conductivity of the new ADB part? Given = 3:
physics-General
physics-
Two sheets of thickness d and 2d and same area are touching each other on their face. Temperature TA , TB , TC shown are in geometric progression with common ratio r = 2. Then ratio of thermal conductivity of thinner and thicker sheet are
Two sheets of thickness d and 2d and same area are touching each other on their face. Temperature TA , TB , TC shown are in geometric progression with common ratio r = 2. Then ratio of thermal conductivity of thinner and thicker sheet are
physics-General
physics-
Heat is conducted across a composite block of two slabs of thickness d and 2d. Their thermal conductivities are 2k and k respectively. All the heat entering the face AB leaves from the face CD. The temperature in °C of the junction EF of the two slabs is :
Heat is conducted across a composite block of two slabs of thickness d and 2d. Their thermal conductivities are 2k and k respectively. All the heat entering the face AB leaves from the face CD. The temperature in °C of the junction EF of the two slabs is :
physics-General
physics-
One end of a 2.35m long and 2.0cm radius aluminium rod 
is held at 200C. The other end of the rod is in contact with a block of ice at its melting point. The rate in 
at which ice melts is [Take latent heat of fusion for ice as 
One end of a 2.35m long and 2.0cm radius aluminium rod is held at 200C. The other end of the rod is in contact with a block of ice at its melting point. The rate in at which ice melts is [Take latent heat of fusion for ice as
physics-General
physics-
The graph shown in the figure represent change in the temperature of 5 kg of a substance as it absorbs heat at a constant rate of 42 kJ min–1 The latent heat of vapourazation of the substance is :
The graph shown in the figure represent change in the temperature of 5 kg of a substance as it absorbs heat at a constant rate of 42 kJ min–1 The latent heat of vapourazation of the substance is :
physics-General
maths-
Consider the circles, 
and 
Statement‐I Tangents from the point P(O, 5) on 
and 
are equal
Statement‐II Point P(O, 5) lies on the radical axis of the two circles.
Consider the circles, and
Statement‐I Tangents from the point P(O, 5) on and are equal
Statement‐II Point P(O, 5) lies on the radical axis of the two circles.
maths-General
maths-
Statement‐I Angle between the tangents drawn from the point P(13,6) to the circle 
is 90.
Statement‐II Point 
lies on the director circle of S.
Statement‐I Angle between the tangents drawn from the point P(13,6) to the circle is 90.
Statement‐II Point lies on the director circle of S.
maths-General
maths-
The common chord of two intersecting circles 
and 
can be seen from their centres at the angles of 90°& 60° respectively If the distance between their centres is equal to 
then the radii of and are‐
The common chord of two intersecting circles and can be seen from their centres at the angles of 90°& 60° respectively If the distance between their centres is equal to then the radii of and are‐
maths-General
maths-
If the two circles, 
and 
touches each other, then‐
If the two circles, and touches each other, then‐
maths-General
maths-
Pair of tangents are drawn from every point on the line 3x+4y=12 on the circle 
Their variable chord of contact always passes through a fixed point whose co‐ordinates are ‐
Pair of tangents are drawn from every point on the line 3x+4y=12 on the circle Their variable chord of contact always passes through a fixed point whose co‐ordinates are ‐
maths-General
