Assertion : The equivalent thermal conductivity of two plates of same thickness in contact (series) is less than the smaller value of thermal conductivity.
Reason : For two plates of equal thickness in contact (series) the equivalent thermal conductivity is given by
`1/K = 1/K_(1) + 1/K_(2)`

Options

A. If both the assertion and reason are true and reason is the correct explanation of the assertion.
B. If both the assertion and reason are true but the reason is not correct explanation of the assertion.
C. If the assertion is true but the reason is false
D. If the both the assertion and reason are false.

Answer

D

Explanation

Equivalent thermal conductivity of two equally thick plates in series combination is given by

`(2)/(K) = 1/(K_1) + 1/(K_2)`
if `K_(1) lt K_(2)`
then `K_(1) lt K lt K_(2)`
Hence assertion and reason both are false.