1
COMEDK 2025 Afternoon Shift
MCQ (Single Correct Answer)
+1
-0
Rods $A$ and $B$ have their lengths in the ratio $1: 2$. Their thermal conductivities are $K_1$ and $K_2$ respectively. The temperatures at the ends of each rod are $\mathrm{T}_1$ and $\mathrm{T}_2$. If the rate of flow of heat through the rods is equal, the ratio of area of cross section of $A$ to that of $B$ is
A
$\frac{2 K_2}{K_1}$
B
$\frac{K_2}{4 K_1}$
C
$\frac{K_2}{K_1}$
D
$\frac{K_2}{2 K_1}$
2
COMEDK 2025 Afternoon Shift
MCQ (Single Correct Answer)
+1
-0
A monoatomic ideal gas, initially at temperature $T_1$, is enclosed in a cylinder fitted with a frictionless piston. The gas is allowed to expand adiabatically to a temperature $\mathrm{T}_2$ by releasing the piston suddenly. If $L$ and $2 L$ are the lengths of the gas column before and after expansion respectively, then $\frac{T_1}{T_2}$ is
A
$2^{3 / 2}$
B
$2^{2 / 3}$
C
$\left(\frac{1}{2}\right)^{2 / 3}$
D
$\left(\frac{1}{2}\right)^{3 / 2}$
3
COMEDK 2025 Afternoon Shift
MCQ (Single Correct Answer)
+1
-0
An ideal gas is expanding such that $P T^2=$ constant. The coefficient of volume expansion of the gas is
A
$\frac{2}{T}$
B
$3 T$
C
$\frac{T}{3}$
D
$\frac{3}{T}$
4
COMEDK 2025 Morning Shift
MCQ (Single Correct Answer)
+1
-0
A block of metal A is connected in series with another block of metal B such that the two metal blocks have the same area of cross sections. The thermal conductivity of metal A is K and the free end of metal A is at $80^{\circ} \mathrm{C}$. The temperature of the interface is $60^{\circ} \mathrm{C}$ and the free end of metal B is at $20^{\circ} \mathrm{C}$. Assuming the two metals have the same thickness, the conductivity of metal B is:
A
$2 K$
B
$4 K$
C
$\frac{K}{2}$
D
$\frac{K}{4}$
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