Page 1 - THERMAL PROPERTIES OF MATTER#141511110123

WORKSHEET-2(Heat transfer, Newton’s law of cooling, qualitative ideas of Blackbody radiation, Wein's
displacement Law, Stefan's law, Greenhouse effect)

1 Which of the following is more close to a blackbody?

(a)Blackboard paint

(b)Green leaves

(c)Red roses

(d)All of the above

2 The earth radiates in the infrared region of the spectrum. The spectrum is correctly given by

(a)Planck’s law of radiation

(b)Stefan’s law of radiation

(c)Wien’s law

(d)None of these

3 A piece of blue glass heated to a high temperature and a piece of red glass at room temperature , are
taken inside a dimly lit room

(a)the blue glass will look blue and red will look as usual

(b)red looks brighter red and blue looks ordinary blue

(c)blue shines like brighter red compared to the red piece

(d)both the pieces will look equally red

4 Heat travels through vacuum by____________________.

5 The predominant mechanism for heat transfer inside a human body is______________.

2
6 The rate of loss of heat through a glass window of area 1000 cm and thickness 0.4 cm when temperature
o
o
inside is 37 C and outside is -5 C is________________________.
-3
-1
-1
-1
(Coefficient of thermal conductivity of glass is 2.2x10 cal s cm K )
7 Explain why:
(a) a body with large reflectivity is a poor emitter.
(b) a brass tumbler feels much colder than a wooden tray on a chilly day.

8 A body cools from 80 °C to 50°C in 5 minutes. Calculate the time it takes to cool from 60 °C to