Two thermometers A and B are calibrated in different scales. When both the termometers are placed in a container filled with hot water the mecury thread in the thermometer A has mvoed through divisions whereas the mercury thread in thermometer B has moved though 15 divisions. The reading on thermometers A and B are `20^(@) and 40^(@)`, respectively. if the lower fixed point fo the thermometer A is `0^(@)`, determinet he lowe fixed pointt of the thermometer B.

Explanation

The difference of temperature readings on A and B are `10^(@) and 15^(@)` respectively.
but `(DeltaA)/(U_(1)-L_(1))=(DeltaB)/(U_(2)-L_(2))`
Where `U_(1),U_(2)` are the upper fixed points and `L_(1),L_(2)` are the lower fixed points of the thermometers A and B.
`(U_(1)-L_(1))/(U_(2)-L_(2))=(10)/(15)=(2)/(3)`
`(20-L_(1))/(U_(1)-L_(1))=(40-L_(2))/(U_(2)-L_(2))implies(U_(1)-L_(1))/(U_(2)-L_(2))=(20-L_(1))/(40-L_(2))`
`(2)/(3)=(20-L_(1))/(40-L_(2))implies(2)/(3)=(20-0)/(40-L_(2))` ltBrgt `80L-2L_(2)=60`
`-2L_(2)=-20`
`L_(2)=10`
`therefore` Lower fixed point of B is `10^(@)`.