Optics Question 184
Question: A 20 cm length of a certain solution causes right-handed rotation of 38°. A 30cm length of another solution causes left-handed rotation of 24°. The optical rotation caused by 30cm length of a mixture of the above solutions in the volume ratio 1 : 2 is
[KCET 2001]
Options:
A) Left handed rotation of 14°
B) Right handed rotation of 14°
C) Left handed rotation of 3°
D) Right handed rotation of 3°
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Answer:
Correct Answer: D
Solution:
As q µ l Volume ratio 1 : 2 in a tube of length 30 cm means 10 cm length of first solution and 20 cm length of second solution .
Rotation produced by 10 cm length of first solution $ {\theta _{1}}=\frac{38{}^\circ }{20}\times 10=19{}^\circ $
Rotation produced by 20cm length of second solution $ {\theta _{2}}=-\frac{24{}^\circ }{30}\times 20=-16{}^\circ $
Total rotation produced = 19° ? 16° = 3°
