Home
Class 11
PHYSICS
A double pan window used for insulating ...

A double pan window used for insulating a room thermally from outside consists of two glass sheets each of area 1 `m^(2)` and thickness `0.01m` separated by `0.05` m thick stagnant air space. In the steady state, the room-glass interface and the glass-outdoor interface are at constant temperatures of `27^(@)C` and `0^(@)C` respectively. The thermal conductivity of glass is `0.8 Wm^(-1)K^(-1)` and of air `0.08 Wm^(-1)K^(-1)`. Answer the following questions.
(a) Calculate the temperature of the inner glass-air interface.
(b) Calculate the temperature of the outer glass-air interface.
(c) Calculate the rate of flow of heat through the window pane.

A

`41.5 W`

B

`31.5 W`

C

`21.5 W`

D

`11.5 W`

Text Solution

Verified by Experts

The correct Answer is:
A

Total thermal resistance is
`R = (t_(1))/(K_(1)A_(1)) + (t_(2))/(K_(2)A_(2)) + (t_(1))/(K_(1)A_(1))`
`R = 2 xx (0.01)/(0.8 xx 1) + (0.05)/(0.08 xx 1) = 0.65 W^(-1) K`
`:.` Heat current, `H = (DeltaT)/(R) = (27-0)/(0.65) = 41.5 W`
Promotional Banner

Topper's Solved these Questions

  • THERMAL PROPERTIES OF MATTER

    NCERT FINGERTIPS|Exercise NCERT Exemplar|8 Videos

  • THERMAL PROPERTIES OF MATTER

    NCERT FINGERTIPS|Exercise Assertion And Reason|10 Videos

  • THERMAL PROPERTIES OF MATTER

    NCERT FINGERTIPS|Exercise Newton'S Law Of Cooling|3 Videos

  • SYSTEM OF PARTICLES AND ROTATIONAL MOTIONS

    NCERT FINGERTIPS|Exercise Assertion And Reason|15 Videos

  • THERMODYNAMICS

    NCERT FINGERTIPS|Exercise Assertion And Reason|15 Videos

Similar Questions

Explore conceptually related problems

A double-pane window consists of two glass sheets each of area 1m^(2) and thickness 0.01m separated by a 0.05 m thick stagnant air space. In the steady state, the room glass interface and the glass outdoor interface are at constant temperature of 27^(@)C and 0^(@)C , respectively. (a) Calculate the rate of heat flow through the window pane. (b) Find the temperatures of other interfaces. [Take: thermal conductivities as K_(glass)=0.8Wm^(-1)K^(-1) and K_(air)=0.08Wm^(-1)K^(-1) ]

A window with double-pane is used for insulating a room thermally from outside. It consists of two glass sheets, each of area A and thickness d with a separation x between them. At equilibrium, the room-glass interface and glass-outside interface are at constant temperature of T_r and T_a respectively. What will the rate of heat flow through the window pane? The thermal conductivity of glass and air are K_1 and K_2 , respectively.

The thermal conductivity of brick is 1.7 W m^(-1) K^(-1) , and that of cement is 2.9 W m^(-1) K^(-1) .What thickness of cement will have same insulation as the brick of thickness 20 cm .

The area of the glass of a window of a room is 10 m^(2) and thickness 2 mm . The outer and inner temperature are 40^(@)C and 20^(@)C respectively. Thermal conductivity of glass in MKS system is 0.2. The heat flowing in the room per second will be

Calculate the rate of loss of heat through a glass window of area 1000 cm^(2) and thickness 0.4 cm when temperature inside is 37^(@)C and outside is -5^@)C . Coefficient of thermal conductivity of glass is 2.2 xx 10^(-3) cal s^(-1) cm^(-1) K^(-1) .

The critical angle for glass air interface is C and for glass water interface is c' . How are C and C' related ?

The critical angle for glass air interface is C and for glass water interface ic C' . How are C and C' related ?

The refractive indices of water and glass with respect to air are 1.2 and 1.5 respectively. The refractive index of glass with respect to water is

For a glass window of area 1500 cm^2 and thickness 0.5 cm, determine the rate of loss of heat if the temperature inside the window is 35^@C and outside is -2^@C . Take, coefficient of thermal conductivity of glass = 2.2 xx 10^(-3) cal s^(-1) cm^(-1) K^(-1)