Assertion: The focal length of an equiconvex lens of radius of curvature R made of material of refractive index μ = 1.5, is R. Reason: The focal length of the lens will be R/2.

Question

Assertion: The focal length of an equiconvex lens of radius of curvature R made of material of refractive index μ = 1.5, is R. Reason: The focal length of the lens will be R/2. (A) If both Assertion and Reason are correct and the Reason is a correct explanation of the Assertion. (B) If both Assertion and Reason are correct but Reason is not a correct explanation of the Assertion. (C) If the Assertion is correct but Reason is incorrect. (D) If the Assertion is incorrect and Reason is correct.

Tardigrade Admin · Accepted Answer

(1/f)=(μ-1)((1/R1)-(1/R2))=(1.5-1)((1/R)-(1/-R)) or f=R.

Q. Assertion : The focal length of an equiconvex lens of radius of curvature $R$ made of material of refractive index $μ = 1.5$ , is $R$ .
Reason : The focal length of the lens will be $R /2$ .

If both Assertion and Reason are correct and the Reason is a correct explanation of the Assertion.

If both Assertion and Reason are correct but Reason is not a correct explanation of the Assertion.

If the Assertion is correct but Reason is incorrect.

If the Assertion is incorrect and Reason is correct.

$\frac{1}{f} = (μ - 1) (\frac{1}{R _{1}} - \frac{1}{R _{2}}) = (1.5 - 1) (\frac{1}{R} - \frac{1}{- R})$
or $f = R$ .

Q. Assertion : The focal length of an equiconvex lens of radius of curvature R made of material of refractive index μ=1.5, is R. Reason : The focal length of the lens will be R/2.