A 28. A capillary of radius r is lowered into a wetting agent with surface tension a and density d.
         (i)    The height h0  to witch the liquid will rise in the capillary is - 
              ​  ​(A)  2 a d g r         ​(B)  4 a d g r         ​(C)  8 a d g r         ​(D)  a 8 d g r  
         ​(ii)  ​ The work done by surface tension is -
            ​    ​(A)  2 πa 2 d g     ​  ​(B)  4 πa 2 d g             ( C )   8 πa 2 d g       (D)  12 πa 2 d g
      ​    ​(iii) The potential energy acquired by the liquid in the capillary is equal to -
    ​            ​ (A) ​ 4 πa 2 d g      (B)  6 πa 2 d g        ( C )   2 πa 2 d g                   ( D )   7 πa 2 d g

Dear student,

i  the rise in capillary is h=2αcosθdgrsince the liquid is sticky then we can consider theta very samll h=2αdgr   option A is correctii work done is the rise i PE PE=hπr2d*g*h2=2αdgr2×πr2d*g2=2πα2dgwork done is equal to PEii option Aiii option CRegards

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