Question

Two rods are of same material and having same length and area. If heat `DeltaQ` flows through them for 12 min when they are joined side by side. If now both the rods are joined in parallel, then the same amount of heat `DeltaQ` will flow in
A. 24 s
B. 3 s
C. 1.5 s
D. 48 s

Answer 1

Correct Answer - B

`Q=KA(Deltatheta)/(l)t :. tprop(1)/(A)`
`(t_1)/(t_2)=(l_1)/(l_2)xx(A_2)/(A_1)=((l_1)/((l)/(2)))xx((2A_1)/(A_1))` (As `Q,K` and `Delta theta` are constant)
`(t_1)/(t_2)=4impliest_2=(t_1)/(4)=(12)/(4)=3s`