Question

6) Assertion (A): A concave lens of very short focal length causes higher divergence than the one with a longer focal length. Reason (R): The degree of convergence or divergence of light rays achieved by a lens is expressed in terms of its power. options. (a) Both A and R are true, and R is the correct explanation of the assertion. (b) Both A and R are true, and R is not the correct explanation of the assertion. (c) A is true, but R is false. (d) A is false, but R is true.​

Answer 1

Answer:

Hey mate...

Explanation:

The correct answer will be option C , The assertion is true but the reason is false... It's because the power of a lens is inversely proportional to its focal length....

Answer 2

(a) Both assertion and reason are true and reason is correct explanation for assertion.

Explanation:

• Concave lens is also called diverging lens.
• It diverge rays incident on it away from normal.
• Any ray incident from infinity diverges on a point on principal axis of lens, this is called focal point of the lens.
• Focal length of a lens is the distance between focal point and pole of lens.
• Focal length of any lens decides the degree convergence or divergence of any lens.
• Degree of convergence or divergence is given by power of lens.
• $Power=\frac{1}{f}$ where f is focal length of lens.
• Power of lens is the reciprocal of focal length.
• Small focal length will cause the angle of divergence to be large and a large focal length will have small angle of divergence.
• Power of lens is inversely proportional to focal length of lens.
• So, large focal length of lens corresponds to its low power and small focal length corresponds to its high power.