Physics 2007 JAMB Past Questions - Question 39: A clinical thermometer is different from other mercury in glass thermometers owing to

Correct Answer

B

Explanation

A clinical thermometer is different from other mercury-in-glass thermometers owing to several key design and functional features that make it suitable for measuring human body temperature. Here are some of the primary differences:

1. Temperature Range: Clinical thermometers are designed to measure the narrow temperature range typically found in the human body (around 35°C to 42°C or 95°F to 108°F), whereas other mercury-in-glass thermometers can have a wider temperature range.

2. Scale Graduation: Clinical thermometers have finer graduations, often marked in 0.1-degree increments, allowing for more precise measurement of small temperature changes in the human body. In contrast, other thermometers may have larger gradations to cover a broader temperature range.

3. Mercury Volume: Clinical thermometers contain a smaller amount of mercury in the bulb, which allows for a quicker response to temperature changes. This is important for accurately measuring the rapid temperature fluctuations that can occur in the human body.

4. Safety Features: Clinical thermometers typically include a constriction in the capillary tube that prevents the backflow of mercury into the bulb. This safety feature prevents accidental exposure to mercury, which is toxic.

5. Ease of Use: Clinical thermometers often have a flexible or bendable tip for more comfortable and safe insertion in body orifices. They are also designed for easy sterilization between uses.

6. Durability: Clinical thermometers are usually constructed to withstand repeated use and sterilization, while other mercury-in-glass thermometers may not be as robust.

7. Color Coding: Clinical thermometers often come with color-coded markings to help users identify the range of normal body temperature more easily.

It's important to note that mercury-in-glass thermometers, including clinical thermometers, are being phased out in many regions due to the environmental concerns associated with mercury. They are being replaced with digital thermometers, which are safer, more accurate, and easier to read.