Multiple Choice

Figure. shows variation of magnification $$m$$ (produced by a thin convex lens) and distance $$v$$ of image from pole of the lens. Which of the following statements are correct?

AFocal length of the lens is equal to intercept on $$v-axis$$
Correct Answer
BFocal length of the lens is equal to inverse of slope of the line
Correct Answer
CMagnitude of intercept on m-axis is equal to unity
Correct Answer
DNone of the above

Solution

Using lens formula : $$\dfrac{1}{v}-\dfrac{1}{u} = \dfrac{1}{f}$$
OR $$1-\dfrac{v}{u} = \dfrac{v}{f}$$ $$\implies$$ $$1-m = \dfrac{v}{f}$$
For focal length : Put $$m =0 $$
We get, $$v = f$$
Thus focal length is equal to the intercept on v-axis.
Slope of line $$S = \dfrac{1}{f}$$ $$\implies f = \dfrac{1}{S}$$
For option C :
Put $$v =0$$ in equation (1), we get $$m = 1$$
Hence magnitude of intercept on m axis is equal to unity.

SIMILAR QUESTIONS

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