# The lower and upper fixed points marked on a mercury-in-glass…

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**The lower and upper fixed points marked on a mercury-in-glass thermometer are 210mm apart. The end of the mercury column in the tube is 49mm above the lower fixed point in a room. What is the temperature of the room in degrees Celsius?**

**A. 23.3****°C**

**B. 30.43****°C**

**C. 49.0****°C**

**D. 16.43****°C**

**QUICK ANSWER…**

**A**

**DETAILS…**** **** **

**To resolve this, you will have to draw a sketch of the two scales and trace the temperature corresponding to 49mm on the degree celsius scale by simple ratio arithmetic manipulation as follows:**

**Data given:**

**Upper fixed point for the mm scale = 210mm**

**Lower fixed point for the mm scale = 0mm (since it is 210mm apart from the upper fixed point)**

**Level of mercury on the mm scale = 49mm (this is the value we need to convert to degrees celsius)**

**Also,**

**Upper fixed point of the celsius scale = 100****°****c**

**Lower fixed point of the celsius scale = 0****°****c**

**Level of mercury on the celsius scale = ???? = x**

**We have a sketch:**

**Now for the right answer to the above question:**

**A is the right answer. 23.33°c****B is incorrect.****C is incorrect.****D is incorrect.**

**KEY-POINTS…**

**You may please note this/these:**

**Even if you use the upper fixed point or the middle point as the pivot, you will still arrive at the same answer, just ensure you do the same thing on both scales.****To avoid avoidable error, you must sketch the both scales and identify their lower and upper fixed points as well as their measurement points.****You must also do the ratio thing, making sure the same arrangement you do with the known scale is same with what you do with the scale containing unknown point.**

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**/ culled from 2020 JAMB-UTME physics past question 31 /**