Optics 1 Question 12
12. A student performed the experiment of determination of focal length of a concave mirror by $u-v$ method using an optical bench of length $1.5 m$. The focal length of the mirror used is $24 cm$. The maximum error in the location of the image can be $0.2 cm$. The 5 sets of $(u, v)$ values recorded by the student (in $cm)$ are : $(42,56),(48,48),(60,40),(66,33),(78,39)$. The data set(s) that cannot come from experiment and is (are) incorrectly recorded, is (are)
(2009)
(a) $(42,56)$
(b) $(48,48)$
(c) $(66,33)$
(d) $(78,39)$
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Answer:
Correct Answer: 12. (c, d)
Solution:
- Values of options (c) and (d) don’t match with the mirror formula.
$$ \frac{1}{v}+\frac{1}{u}=\frac{1}{f} $$
