Question

Why level of mercury should change when bulb of thermometer is brought in contact with another object?

Answer 1

It is because a liquid changes its volume relative to its temperature and should be changed at all when the bulb of the thermometer is in contact with another object.

This usually denotes temperature changes and includes other projects taken at right contact levels.

It has been discovered in pertaining with relative temperature changes.

Answer 2

the change in the reading indicates that the temperature varies with different objects

so the temperature changes when the bulb is in contact with another object.