Question

Assertion (A): When the temperature rises, the Sensitivity of the bubble tube increases

Reason: Air expands more than liquid used in the bubble tube.

Select the correct answer from the following:

1. Both A and R are true and R is the correct explanation of A
2. Both A and R are true and R is not a correct explanation of A
3. A is true but R is false.
4. A is false but R is true

Answer 1

Correct Answer - Option 4 : A is false but R is true

Explanation:

Sensitivity of bubble tube:

(i) The sensitiveness of a level tube is defined as the angular value of one division marked on the tube.

(ii) The sensitiveness of a bubble tube can be increased by:

• Increasing the internal radius of the tube.
• Increasing the diameter of the tube.
• Increasing the length of the bubble.
• Decreasing the roughness of the walls, and
• Decreasing the viscosity of the liquid

(iii) With a rise in temperature the liquid expands. Hence the bubble shortens and consequently its sensitivity decreases.

So, Assertion is wrong.

Level Tube :

(i) Also known as Bubble Tube consists of a glass tube placed in a brass tube which is sealed with plaster of paris. The whole of the interior surface or the upper half is accurately ground so that its longitudinal section, is an arc of a circle. 

(ii) Level tube is filled with either or alcohol, the remaining space is occupied by an air bubble (Spirituous liquids are used because they are less viscous, i.e., flow more freely than water. Also, these liquids have a relatively low freezing point but a greater expansion than water.)

So Reason is the correct.