Two rods of same length and material transfer given amount of heat in 12 s, when they are joined end to end. When they are joined parallelly then they will transfer same amount of heat in same conditions in

Options

A. 24 s
B. 3 s
C. 1.5 s
D. 48 s

Answer

B

Explanation

When rods are joined is series,
`Q=(KA Delta T)/(2l) xx 12` ….(i)
When rods are joined lengthwise,
`Q=(K(2A)DeltaT)/(l)t` …(ii)
From equation (i) and (ii) `(KA Delta T)/(2l) xx 12` = `Q=(K(2A)DeltaT)/(l)xxt implies` t=3 sec