MCQ
A reversible heat engine converts one-fourth of the heat input into work. When the temperature of the sink is reduced by $52\, K$, its efficiency is doubled. The temperature in Kelvin of the source will be ...... .
- A$256$
- ✓$208$
- C$104$
- D$52$
✓
Answer
Correct option: B.
$208$
b
$\eta=\frac{1}{4}=1-\frac{ T _{2}}{ T _{1}}$
$\eta=\frac{1}{4}=1-\frac{ T _{2}}{ T _{1}}$
$\frac{ T _{2}}{ T _{1}}=\frac{3}{4}$
$\frac{ T _{2}-52}{ T _{1}}=\frac{1}{2}$
Need a full question paper?
Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.
Explore more
Similar questions
The resistance of an incandescent lamp is
We have a galvanometer of resistance $25\,\Omega $. It is shunted by a $2.5\,\Omega $ wire. The part of total current that flows through the galvanometer is given as
→The change in the value of acceleration of earth towards sun, when the moon comes from the position of solar eclipse to the position on the other side of earth in line with sun is: (mass of the moon $= 7.36 \times 10^{22}\,kg,$ radius of the moon's orbit $= 3 .8 \times 10^8\,m$ ).
→A block of mass $m$ slides from rest at a height $H$ on a frictionless inclined plane as shown in the figure. It travels a distance $d$ across a rough horizontal surface with coefficient of kinetic friction $\mu$ and compresses a spring of spring constant $k$ by a distance $x$ before coming to rest momentarily. Then the spring extends and the block travels back attaining a final height of $h$. Then,
→The reactance of a $25\,\mu F$ capacitor at the ac frequency of $4000\, Hz$ is
→$(A)$ $C_3H_6O$ $\mathop {\xrightarrow{{NaCN}}}\limits_{{H_2}S{O_4}} $ cyanohydrin of $(A).$ If the cyanohydrin is optically active, then the possible structure of $(A)$ is
→The frequency of oscillation of the springs shown in the figure will be
Assume the aerodynamic drag force on $a$ car is proportional to its speed. If the power output from the engine is doubled, then the maximum speed of the car.
→A body falling from the rest has a velocity $v$ after it falls through a height $h$. The distance it has to fall down further for its velocity to become double, will be $...............\,h$
→The bob of a simple pendulum (mass m and length $ l$) dropped from a horizontal position strikes a block of the same mass elastically placed on a horizontal frictionless table. The K.E. of the block will be
→