Physics MCQs for NEET — Practice Questions with Answers

The NCERT text clearly states: '...when the temperature of body... and its surrounding medium are different, heat transfer takes place between the system and the surrounding medium, until the body and the surrounding medium are at the same temperature.' This highlights the essential role of temperature difference in heat transfer.

The summary explicitly provides the relation: '$T_C = T – 273.15$'. Rearranging this gives $T = T_C + 273.15$. The text also mentions 'K = °C + 273.15'.

Point 9 in the summary lists: 'The three modes of heat transfer are conduction, convection and radiation.' Absorption is a process related to heat but not a mode of transfer itself.

Point 8 in the summary states: 'The latent heat of vaporisation (Lv) is the heat per unit mass required to change a substance from liquid to the vapour state without change in the temperature and pressure.'

The text states: 'For a body, which is a perfect radiator, the energy emitted per unit time (H) is given by $H = A\sigma T^4$'. This shows the proportionality to the fourth power of the absolute temperature.

The introduction mentions: 'Along the way, you will find out why blacksmiths heat their iron ring before fitting on the rim of a wooden wheel of a horse cart'. This action is done to expand the iron ring due to heating (thermal expansion), allowing it to fit over the wooden rim. Upon cooling, it contracts and forms a tight fit.

The introduction states: 'You will also learn what happens when water boils or freezes, and its temperature does not change during these processes even though a great deal of heat is flowing into or out of it.' This describes the concept of latent heat, where the supplied heat energy causes a phase change rather than a temperature change.

Point 6 in the summary provides the relation: '$\alpha_v = 3 \alpha_l$'.

Point 11 in the summary states: 'Newton’s Law of Cooling says that the rate of cooling of a body is proportional to the excess temperature of the body over the surroundings'. This 'excess temperature' is the difference between the body's temperature and the surrounding's temperature.

The text states: 'One, therefore, defines a dimensionless fraction e called emissivity and writes, H = $Ae\sigma T^4$'. It also clarifies that 'e = 1 for a perfect radiator'.