# Temperature Units Conversion

## Homework Statement

A thermometer has its lower and upper fixed points marked as 10 and 80. When it reads 40, what is the corresponding temperature on Centrigrade scale?

## The Attempt at a Solution

I have no idea of solving such type of questions.

gneill
Mentor
How can one answer if the 10 and 80 points on the mystery thermometer are not tied to some physical circumstance such as a a boiling point, or freezing point, or some other thing with a definite temperature benchmark?

I think by upper and lower fixed points it means the b.p and f.p. respectively.

tiny-tim
Homework Helper
Hi Abdul! So 0°C is 10 and 100°C is 80 …

so what do you think 40 is ? gneill
Mentor
Hi Abdul! So 0°C is 10 and 100°C is 80 …

so what do you think 40 is ? What if it happens to be a limited range Fahrenheit thermometer? tiny-tim
Homework Helper
What if it happens to be a limited range Fahrenheit thermometer? i've no idea what you're talking about have you got a temperature? A temperature difference of 70 on new scale corresponds to a temperature difference of 100 C. So 1 unit of new scale corresponds to 100/70 C
40 units correspond to 57.14C.

Is it right?

gneill
Mentor
A temperature difference of 70 on new scale corresponds to a temperature difference of 100 C. So 1 unit of new scale corresponds to 100/70 C
40 units correspond to 57.14C.

Is it right?

How do you know that the temperature difference of 70 on the mystery scale corresponds to a temperature difference of 100 on the Celsius scale? You have no information on how the mystery thermometer is calibrated. What if it reads in degrees K? Or in 100's of degrees K?

Borek
Mentor
I have a bath thermometer that starts at 20 and ends at 40. 20 doesn't mean freezing, and 40 doesn't mean boiling, these are just Celsius degrees.

Either there is some additional context to the question, or there is no answer.

tiny-tim
Homework Helper
A temperature difference of 70 on new scale corresponds to a temperature difference of 100 C. So 1 unit of new scale corresponds to 100/70 C
40 units correspond to 57.14C.

Is it right?

No. 0°C is 10 and 100°C is 80, and 40 is how many sevenths from 10 to 80?

I have a bath thermometer that starts at 20 and ends at 40. 20 doesn't mean freezing, and 40 doesn't mean boiling, these are just Celsius degrees.

Either there is some additional context to the question, or there is no answer.

May be there is some terminology of upper and lower fixed points in thermometry, like they might mean b.p. and f.p. resp. If you still think the question is unclear lets assume so and 40 is how many sevenths from 10 to 80?

I don't understand that sentence. Can you elaborate (perhaps by giving an example)?