question_answer

A capillary tube when immersed vertically in a liquid records a rise of 3 cm. If the tube is held immersed in the liquid at an angle of \[60{}^\circ \] with the vertical, the length of the liquid column along the tube will be:

A)  3 cm                                     

B)  2\[\sqrt{2}\]cm

C)  15 cm                                  

D)  6 cm

Correct Answer: D

Solution :

 If capillary tube is fitted from the vertical angle \[\theta ,\] then vertical height h or liquid column remains same but the length of liquid in capillary increases such that \[\cos \theta =\frac{h}{l}\]                 \[\Rightarrow \]                               \[l=\frac{h}{\cos \theta }\]                          ..(1) Now, putting the given values of h and 9 in Eq.(1) \[l=\frac{3}{\cos 60}=\frac{3}{1/2}=6cm\]