Question: 100% NCERT covered from Particular Keyword.Explanations are 100% from NCERT | [Difficult level: Easy] From NCERT NEET20019.
The unit of thermal conductivity is
(a) W m–1 K–1 (b) J m K–1
(c) J m–1 K–1 (d) W m K–1 (NEET 2019)
Answer: a
[Rememer or solve]
- Unit = 1 W m⁻¹ K⁻¹
- 1 W m⁻¹ K⁻¹ = 6.938 Btu in/hft² °F
Reference: NCERT Physics Page 210
- The constant of proportionality K is called the
thermal conductivity of the material. The
greater the value of K for a material, the more
rapidly will it conduct heat.
- The SI unit of K is
J s^–1 m^–1 K^–1 or 1 W m⁻¹ K⁻¹
- Gases are poor conductors,
and have the low thermal conductivity of air.
- Houses
made of concrete roofs get very hot during
summer days because thermal conductivity of
concrete (though much smaller than that of a
metal) is still not small enough. Therefore, people,
usually, prefer to give a layer of earth or foam
insulation on the ceiling
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| NCERT |
Solution:
