Assertion A biconvex lens of focal length 10 cm is split into two equals parts by a plane parallel to its principal axis. The focal length of the each part will be 20 cm. Reason Focal length does not depend on the radii of curvature of two surfaces.

Question

Assertion A biconvex lens of focal length 10 cm is split into two equals parts by a plane parallel to its principal axis. The focal length of the each part will be 20 cm. Reason Focal length does not depend on the radii of curvature of two surfaces. (A) Both assertion and reason are true and reason is the correct explanation of assertion (B) Both assertion and reason are true but reason is not the correct explanation of assertion (C) Assertion is true but reason is false (D) Both assertion and reason are false

Tardigrade Admin · Accepted Answer

Since, lens is cut into two equal parts by a plane parallel to its principal axis, so both the part still to be biconvex.

Hence, focal length of each part will remain as before ie, 10 cm.
Focal length of biconvex lens

\frac{1}{f} = (μ_{g} - 1) (\frac{1}{R _{1}} - \frac{1}{R _{2}})

where

R_{1}

and

R_{2}

be the radii of curvature of two surfaces.

Q. Assertion A biconvex lens of focal length 10 cm is split into two equals parts by a plane parallel to its principal axis. The focal length of the each part will be 20 cm. Reason Focal length does not depend on the radii of curvature of two surfaces.

Both assertion and reason are true and reason is the correct explanation of assertion

Both assertion and reason are true but reason is not the correct explanation of assertion

Assertion is true but reason is false

Both assertion and reason are false

Q. Assertion A biconvex lens of focal length 10 cm is split into two equals parts by a plane parallel to its principal axis. The focal length of the each part will be 20 cm.
Reason Focal length does not depend on the radii of curvature of two surfaces.