Question
When we heat an object, it expands. Is work done by the object in this process ? Is heat given to the object equal to the increase in its internal energy?
✓
Answer
When we heat an object, it expands, i.e. its volume increases.
Work done by the system, $\Delta\text{W}=\text{P}\Delta\text{V}$
Using the first law of thermodynamics, we get,
$\Delta\text{Q}=\Delta\text{U}+\Delta\text{W}$
Since the volume changes, $\Delta\text{W}$ has some non-zero positive value. Thus, heat given to the object is not equal to the increase in the internal energy of the system.
Work done by the system, $\Delta\text{W}=\text{P}\Delta\text{V}$
Using the first law of thermodynamics, we get,
$\Delta\text{Q}=\Delta\text{U}+\Delta\text{W}$
Since the volume changes, $\Delta\text{W}$ has some non-zero positive value. Thus, heat given to the object is not equal to the increase in the internal energy of the system.
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
(I) Draw a ray diagram for the formation of image by a Cassegrain telescope.
(II) Why these types of telescopes are preferred over refracting type telescopes.
(II) Why these types of telescopes are preferred over refracting type telescopes.
How are electromagnetic waves produced? What is the source of energy carried by a propagating electromagnetic wave? Identify the electromagnetic radiations used:
- In remote switches of household electronic devices.
- As diagnostic tool in medicine.
- Using de Broglie's hypothesis, explain with the help of a suitable diagram, Bohr's second postulate of quantization of energy levels in a hydrogen atom.
- The ground state energy of hydrogen atom is - 13.6 eV. What are the kinetic and potential energies of the electron in this state?
The potential difference between the terminals of a battery of emf 6.0V and internal resistance $1\Omega$ drops to 5.8V when connected across an external resistor. Find the resistance of the external resistor.
→What are isotopes? Explain with an example how the average mass can be obtained from the relative proportions of different isotopes of the same element.
A zener diode is fabricated by heavily doping both p- and n- sides of the junction. Explain, why? Briefly explain the use of zener diode as a de voltage regulator with the help of a circuit diagram.
- For a glass prism $(\mu =\sqrt{3} )$ the angle of minimum deviation is equal to the angle of the prism. Calculate the angle of the prism.
- Draw ray diagram when incident ray falls normally on one of the two equal sides of a right angled isosceles prism having refractive index $\mu = \sqrt{3} . $
A sinusoidal voltage of peak value $283 V$ and frequency $50 Hz$ is applied to a series $L C R$ circuit in which $R =3 \Omega, L=25.48 mH$, and $C =796 \mu F$. Find (a) the impedance of the circuit; (b) the phase difference between the voltage across the source and the current; (c) the power dissipated in the circuit; and (d) the power factor.
→- Six lead-acid type of secondary cells each of emf 2.0 V and internal resistance $0.015\Omega$ are joined in series to provide a supply to a resistance of $8.5\ \Omega.$ What are the current drawn from the supply and its terminal voltage?
- A secondary cell after long use has an emf of 1.9 V and a large internal resistance of $380\ \Omega$ What maximum current can be drawn from the cell? Could the cell drive the starting motor of a car?
Three circuits, each consisting of a switch ‘S’ and two capacitors, are initially charged, as shown in the figure. After the switch has been closed, in which circuit will the charge on the left-hand capacitor (i) increase, (ii) decrease and (iii) remain same? Give reasons.
