Download App

11. thermodynamics — Physics STD 11 Science — Question

Gujarat BoardEnglish MediumSTD 11 SciencePhysics11. thermodynamics1 Mark
MCQ
A Carnot's engine works as a refrigerator between $250\, K$ and $300\, K$. It receives $500\, cal$ heat from the reservoir at the lower temperature. The amount of work done in each cycle to operate the refrigerator is ..... $J$
  • ✓
    $420$
  • B
    $2100$
  • C
    $772$
  • D
    $2520$
✓

Answer

Correct option: A.
$420$
a
Given: Temperature of cold body, $T_2= 250\,K$ temperature of hot body; $T_1  = 300\, K$ Heat received, $Q_2= 500\, cal$ work done, $W =$  ?

Effociency$ = 1 - \frac{{{T_2}}}{{{T_1}}} = \frac{W}{{{Q_2} + W}}$

$ \Rightarrow 1 - \frac{{250}}{{300}} = \frac{W}{{{Q_2} + W}}$

$W = \frac{{{Q_2}}}{5} = \frac{{500 \times 4.2}}{5}\,\,J = 420\,J$

Need a full question paper?

Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.

Start Generating Free

Explore more

More "M.C.Q (1 Marks)" from 11. thermodynamics→11. thermodynamics — all question types→Physics STD 11 Science question papers→Gujarat Board STD 11 Science question papers→Gujarat Board question paper generator→

Similar questions

A barometer kept in an elevator reads $76 \,cm$ when it is at rest. If the elevator goes up with some acceleration, the reading will be .......... $cm$
→
The reading of spring balance when a block is suspended from it in air, is $60\,N$. This reading is changed to $40\, N$ when the block is immersed in water. The specific density of the block is
→
As observed from earth, the sun appears to move in an approximate circular orbit. For the motion of another planet like mercury as observed from earth, this would.
→
The bob $A$ of simple pendulum is released when the string makes an angle of $45^o$ with the vertical. It hits another bob $B$ of the same material and same mass kept at rest on the table. If the collision is elastic, then
→
A particle is released from rest at the point $x = a$ and moves along the $x$ axis subject to the potential energy function $U(x)$ shown. The particle:
→
A mass of material exists in its solid format its melting temperature $0\,^o  C$. The following processes then occur to the material

Process $-1$:An amount of thermal energy $Q$ is added to the material and $\frac{2}{3}$ of the material melts.

Process $-2$:An identical additional amountof thermal energy $Q$ is added to the materlal is now a liquid at $4\,^o C$

........ $^oC$ is the ratio of the latent heat of fusion to the specific heat of the liquid for this material.

→
A missile is fired for maximum range at your town from a place $100\, km$ away from you. If the missile is first detected at its half way point, how much warning time will you have ? (Take $g = 10\, m/s ^2$) the maximum height of the missile is
→
The stationary wave $y = 2a\sin kx\cos \omega \,t$ in a closed organ pipe is the result of the superposition of $y = a\sin (\omega \,t - kx)$ and
→
A uniform rope of mass $6\,kg$ hangs vertically from a rigid support. A block of mass $2\,kg$ is attached to the free end of the rope. A transverse pulse of wavelength $0.06\,m$ is produced at the lower end of the rope. The wavelength of the pulse when it reaches the top is (in $m$ )
→
When a bicycle is in motion, the force of friction exerted by the ground on the two wheels is such that it acts
→