Physics-
General
Easy
Question
The temperature of the two outer surfaces of a composite slab, consisting of two materials having coefficients of thermal conductivity 
and 2 and thickness 
and 4, respectively are 
and 
. The rate of heat transfer through the slab, in a steady state is 
, with 
equals to
- 1/3
- 2/3
- 1/3
The correct answer is: 1/3
Let the temperature of common interface be 
. Rate of heat flow
=
And 
=
In steady state, the rate of heat flow should be same in whole system 
=
(i)
Hence, heat flow from composite slab is
= 
(ii)
Accordingly, 
(iii)
By comparing Eqs. (ii) and (iii), we get
Related Questions to study
physics-
A solid material is supplied with heat at constant rate and the temperature of the material changes as shown. From the graph, the false conclusion drawn is
A solid material is supplied with heat at constant rate and the temperature of the material changes as shown. From the graph, the false conclusion drawn is
physics-General
physics-
The energy distribution 
with the wavelength 
for the black body radiation at temperature 
is shown in the figure. As the temperature is increased the maxima will
According to Wien’s displacement law 
. Hence, it temperature increases 
decreases 
peak of the 
curve shift towards left
. Hence, it temperature increases decreases peak of the curve shift towards leftThe energy distribution with the wavelength for the black body radiation at temperature is shown in the figure. As the temperature is increased the maxima will
physics-General
According to Wien’s displacement law . Hence, it temperature increases decreases peak of the curve shift towards left
. Hence, it temperature increases decreases peak of the curve shift towards leftphysics-
A metal rod of length 
has cross sectional areas 
and 
as shown in figure. The ends are maintained at temperatures 
and 
. The temperature at middle point 
is
Let 
be temperature of middle point and in series rate of heat flow is same
be temperature of middle point and in series rate of heat flow is sameA metal rod of length has cross sectional areas and as shown in figure. The ends are maintained at temperatures and . The temperature at middle point is
physics-General
Let be temperature of middle point and in series rate of heat flow is same
be temperature of middle point and in series rate of heat flow is same
physics-
The coefficient of thermal conductivity of copper is nine times that of steel. In the composite cylindrical bar show in figure, what will be the temperature at the junction of copper ad steel?
Let the temperature of junction be 
3
12
3
12
The coefficient of thermal conductivity of copper is nine times that of steel. In the composite cylindrical bar show in figure, what will be the temperature at the junction of copper ad steel?
physics-General
Let the temperature of junction be
3
12
3
12
Maths-
Which function is shown in graph?
Which function is shown in graph?
Maths-General
Maths-
Which function is shown in graph?
Which function is shown in graph?
Maths-General
Maths-
Which function is shown in graph?
Which function is shown in graph?
Maths-General
physics-
Five rods of same dimensions are arranged as shown in figure. They have thermal conductivities 
When points 
are maintained at different temperature, no heat would flow through central rod, if
The equivalent electrical circuit, figure in these cases is of Wheatstone bridge. No current would flow through central rod 
when the bridge is balanced. The condition for balanced Wheatstone bridge is 
(in terms of resistances)
or 
Or
when the bridge is balanced. The condition for balanced Wheatstone bridge is (in terms of resistances) or Or
Five rods of same dimensions are arranged as shown in figure. They have thermal conductivities When points are maintained at different temperature, no heat would flow through central rod, if
physics-General
The equivalent electrical circuit, figure in these cases is of Wheatstone bridge. No current would flow through central rod when the bridge is balanced. The condition for balanced Wheatstone bridge is (in terms of resistances)
or
Or
when the bridge is balanced. The condition for balanced Wheatstone bridge is (in terms of resistances) or Or
physics-
If two metallic plates of equal thicknesses and thermal conductivities 
and 
are put together face to face and a common plate is constructed, then the equivalent thermal conductivity of this plate will be
In series, 
If two metallic plates of equal thicknesses and thermal conductivities and are put together face to face and a common plate is constructed, then the equivalent thermal conductivity of this plate will be
physics-General
In series,
physics-
The graph, shown in the adjacent diagram, represents the variation of temperature 
of two bodies, and 
having same surface area, with time (
) due to the emission of radiation. Find the correct relation between the emissivity and absorptivity power of the two bodies.
Rate of cooling 
emissivity(e)
From the graph,
Further emissivity (
)
absorptive power (
) (good absorbers are good emitters also)
emissivity(e)From the graph,
Further emissivity (
) absorptive power () (good absorbers are good emitters also)The graph, shown in the adjacent diagram, represents the variation of temperature of two bodies, and having same surface area, with time () due to the emission of radiation. Find the correct relation between the emissivity and absorptivity power of the two bodies.
physics-General
Rate of cooling emissivity(e)
From the graph,
Further emissivity () absorptive power () (good absorbers are good emitters also)
emissivity(e)From the graph,
Further emissivity (
) absorptive power () (good absorbers are good emitters also)maths-
Apply SinC+SinD formula
maths-General
Apply SinC+SinD formula
maths-
Value of 
is
Value of is
maths-General
Maths-
What is 
for two mutually exclusive sets A and B?
What is for two mutually exclusive sets A and B?
Maths-General
Maths-
Which of the following is set representing neither A nor B?
Which of the following is set representing neither A nor B?
Maths-General
Maths-
Which of the following is set representing B but not A?
Which of the following is set representing B but not A?
Maths-General
