1

GATE ME 2006

A $100$ $W$ electric bulb was switched on in a $2.5 \times 3 \times 3m$ size thermally insulated room having temperature of ${20^0}C.$ Room temp at the end of $24$ hours will be
A
${321^ \circ }C$
B
${341^ \circ }C$
C
${450^ \circ }C$
D
${470^ \circ }C$
2

GATE ME 2006

With an increase in the thickness of insulation around a circular pipe, heat loss to surroundings due to
A
Convection increases, while that due to conduction decreases
B
Convection decreases, while that due to conduction increases
C
Convection and conduction decreases
D
Convection and conduction increases
3

GATE ME 2005

Heat flows through a composite slab, as shown below. The depth of the slab is $1$ $m.$ the $k$ values are in $W/m. K.$ The overall thermal resistance in $K/W$ is
A
$17.2$
B
$21.9$
C
$28.6$
D
$39.2$
4

GATE ME 2003

Heat is being transferred by convection from water at ${48^ \circ }C$ to a glass plate whose surface that is exposed to the water is at ${40^0}C.$ The thermal conductivity of water is $0.6$ $W/mK$ and the thermal conductivity of glass is $1.2$ $W/mK.$ The spatial gradient of temp in the water at the water glass interface is
$dT/dy = 1 \times {10^4}\,\,K/m...$

The value of the temperature gradient in the glass at the water-glass interface in $K/m$ is

A
$- 2 \times {10^4}$
B
$0.00$
C
$0.5 \times {10^4}$
D
$2 \times {10^4}$