Question

Which one of the following ray diagrams (for a concave/diverging lens) is correct?

• A.

  

• B.

  

• C.

  

• D.

  

Answer 1

The Correct Option is C

Reasoning (Key ray rules for a concave lens):

• A ray
  parallel to the principal axis after refraction appears to
  diverge from the focus on the same side.
• A ray directed
  towards the focus on the incident side emerges
  parallel to the principal axis.
• A ray through the
  optical centre goes
  undeviated.

In option (C), the incident ray is aimed towards the lens’s near focus \(F\) (shown by a dashed extension); after refraction it emerges
parallel to the principal axis — exactly matching rule 2. Therefore, (C) is correct.

\[ \text{Concave lens: } \begin{cases} \text{towards } F \;\Rightarrow\; \text{emerges parallel},\\ \text{parallel} \;\Rightarrow\; \text{appears from } F. \end{cases} \]

Why others are wrong (brief): (B) makes a parallel ray pass through the far focus (that’s for a convex lens, not concave). (D) shows parallel rays remaining parallel after the lens (concave lens should diverge them). (A) does not satisfy any standard concave-lens rule as drawn.