A : In viewing through a magnifying glass, angular magnification decreases if the eye is moved back.
R : Angle subtended at the eye becomes slightly less than the angle subtended at the lens.

Options

A. If both Assertion & Reason are true and the reason is the correct explanation of the assertion, then mark (1).
B. If both Assertion & Reason are true but the reason is not the correct explanation of the assertion, then mark (2).
C. If Assertion is true statement but Reason is false, then mark (3).
D. If both Assertion and Reason are false statements, then mark (4).

Answer

To solve the problem, we need to analyze the assertion (A) and the reason (R) provided in the question regarding the behavior of angular magnification when using a magnifying glass.

### Step 1: Understanding Angular Magnification
Angular magnification (M) is defined as the ratio of the angle subtended by the image (β) at the eye to the angle subtended by the object (α) at the eye when viewed without the magnifying glass. Mathematically, it can be expressed as:
\[ M = \frac{\beta}{\alpha} \]

### Step 2: Effect of Moving the Eye Back
When the eye is moved back from the lens of the magnifying glass, the angle subtended by the image (β) decreases. This is because the distance between the eye and the image increases, leading to a smaller angle being subtended at the eye.

### Step 3: Analyzing the Assertion (A)
The assertion states that the angular magnification decreases if the eye is moved back. Since we have established that β decreases when the eye is moved back, and α remains relatively constant (as the object distance does not change significantly), the overall value of M will decrease. Therefore, the assertion (A) is true.

### Step 4: Analyzing the Reason (R)
The reason states that the angle subtended at the eye becomes slightly less than the angle subtended at the lens. When the eye moves back, the angle subtended at the eye indeed becomes less than the angle subtended at the lens, which is true. Thus, the reason (R) is also true.

### Step 5: Conclusion
Both the assertion (A) and the reason (R) are true, and the reason correctly explains the assertion. Therefore, we can conclude that the statement is correct.

### Final Answer:
Both A and R are true, and R is the correct explanation for A.

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