Single Choice

The focal length of converging lens are $$ { f }_{ v }\ and\ { f }_{ r }$$ for violet and red light respectively,then

A$$ { f }_{ v }>{ \ f }_{ r }$$
B$$ { f }_{ v }={ \ f }_{ r }$$
C$$ { f }_{ v }<{ \ f }_{ r }$$
Correct Answer
DAny of the three is possible depending on the value of the average refractive index $$ \mu $$

Solution

The focal length for the particular light is given as:
$$f=\dfrac{R}{2(\mu-1)}$$

We know that the wavelength of red color is more than that of a violet color.
$$\lambda_{red}>\lambda_{violet}$$

Therefore, $$\mu_{red}<\mu_{violet}$$

Considering the value of the refractive indices for the two colors, it can be concluded that
$$f_{v}

SIMILAR QUESTIONS

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