Question

Fig (a–d) shows a student reading a doctor’s thermometer. Which of the figure indicates the correct method of reading temperature?

• A.
• B.
• C.
• D.

Answer 1

The correct option is A

Explanation for the correct options:

Option A:

1. .A glass thermometer can be a little tricky to read since it’s measured with lines. Hold the thermometer up to eye level, and see where the line of mercury ends. That will be your temperature.
2. The best way to read the thermometer is to keep it straight in front of the eyes and to check the temperature read.
3. Cohesive force between glass and mercury gives exact reading when the thermometer is horizontal.

Explanation for the incorrect options:

Option B:

1. As the thermometer is tilted up to some angle with respect to the horizontal.
2. As the shape made by mercury and glass due to cohesive force between them is convex meniscus type.
3. It will not be properly readable due to the inclination of the thermometer.
4. Hence option B is incorrect.

Option C:

1. As it is not exactly straight to the reader's eye. It is up to her neck level.
2. So again, the shape made by mercury and glass due to cohesive force between them is convex meniscus type.
3. So this is also not a proper way to read a thermometer.
4. Hence option C is incorrect.

Option D:

1. In this case, she is holding the thermometer from the wrong end. i.e she is holding the thermometer from the mercury bulb.
2. So this is also not the correct way to read out a thermometer.
3. Hence option D is incorrect.

Thus the correct option is option A.