NEET Physics Question - Thermal Physics

A Centigrade and a Fahrenheit thermometer are dipped in boiling water. The water temperature is lowered until the Fahrenheit thermometer registers $140^\circ\text{F}$. What is the fall in temperature as registered by the centigrade thermometer? (1990)

$80^\circ\text{C}$

$60^\circ\text{C}$

$40^\circ\text{C}$

$30^\circ\text{C}$

Solution:

Initial temperature of boiling water is $212^\circ\text{F}$. Fall in Fahrenheit $= 212^\circ\text{F} - 140^\circ\text{F} = 72^\circ\text{F}$. Using $\Delta C = \frac{5}{9} \Delta F$, fall in Celsius $= \frac{5}{9} \times 72 = 40^\circ\text{C}$.

Rankers Physics

Thermal Properties of Matter

Solution:

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