Question

A vertical glass jar is filled with water at 10oC. It has one thermometer at the top and another at the bottom. The central region of the jar is gradually cooled. It is found that the bottom thermometer reads 4oC earlier than the top thermometers and the top thermometer reads 0oC earlier than the bottom thermometer. This happens because:

Solution

Correct option is

Water expands when cooled from 4oC to 0oC

On cooling, the water becomes of highest density at 4oC and then it goes down. Therefore bottom thermometer reads 4oC earlier, because the temperature of the water at the top will be more than 4oC.

SIMILAR QUESTIONS

Q1

A metal ball immersed in alcohol weighs W1 at 00C and W2 at 59oC. The coefficient of cubical expansion of the metal is less than that of alcohol. Assuming that the density of metal is large compared to that of alcohol, it can be show that:

Q2

Two straight metallic strips each of thickness t and length L are rivetted together. Their coefficients of linear expansions are   If they are heated through temperature , the bimetallic strip will bend to form an arc of radius:

Q3

A pendulum clock is 5 sec fast at temperature of 15oC and 10 seconds slow at a temperature of 30oC. At what temperature does it give the correct time?

Q4

A thermometer is graduated in millimeters. It registers – 3 mm when the bulb of thermometer is in pure melting ice and 22 mm when the thermometer is in steam at a pressure of 1 atmosphere. The temperature in oC when the thermometer registers 13 mm is:

Q5

The resistance of a resistance thermometer has values 2.71 and 3.70 ohm at 10oC and 100oC. The temperature at which the resistance is 3.26 ohm is:

Q6

The standard fixed point for temperature measurements in use today is:

Q7

A test tube containing water is placed in boiling water so that its mouth remains outside the boiling water. Choose the wrong statement:

Q8

What extinguishes a fire most quickly?

Q9

A 10 kg iron bar (specific heat 0.11 cal/gm-oC) at 80oC is placed on a block of ice. How much ice melts?

Q10

A metallic ball has spherical cavity at its centre. If the ball is heated, what happens to the cavity?