JEE Main & Advanced Physics Fluid Mechanics, Surface Tension & Viscosity / द्रव यांत्रिकी, भूतल तनाव और चिपचिपापन Question Bank Assertion and Reason

  • question_answer
    Assertion             :               When height of a tube is less than liquid rise in the capillary tube, the liquid does not overflow. Reason         :           Product of radius of meniscus and height of liquid in capillary tube always remains constant. 

    A) If both assertion and reason are true and the reason is the correct explanation of the assertion.

    B) If both assertion and reason are true but reason is not the correct explanation of the assertion.

    C) If assertion is true but reason is false.

    D) If the assertion and reason both are false.

    E) If assertion is false but reason is true.

    Correct Answer: A

    Solution :

    \[h=\frac{2T}{Rdg}\] Þ\[hR=\frac{2T}{Rdg}\] \ \[hR=\text{constant}\] Hence when the tube is of insufficient length, radius of curvature of the liquid meniscus increases, so as to maintain the product hR a finite constant. i.e. as h decreases, R increases and the liquid meniscus becomes more and more flat, but the liquid does not overflow.


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