Question: Assertion (A) : The magnifying power of a compound microscope is negative. Reason (R) : The final image formed is erect with respect to the object.

Step 1 (Governing Principle & Definitions): [0.25 Mark]

The magnifying power ($m$) of a compound microscope is defined as the product of the linear magnification of the objective lens ($m_o$) and the angular magnification of the eyepiece ($m_e$):

Where $m_o = \frac{h'}{h} = -\frac{v_o}{u_o}$ (inverted image) and $m_e$ is the magnification of the eyepiece acting as a simple magnifier.

Step 2 (Step-by-Step Analysis): [0.5 Mark]

• Analysis of Assertion (A): The objective lens forms a real, inverted image of the object. Thus, $m_o$ is negative. The eyepiece then magnifies this image. The final image formed by a compound microscope is inverted with respect to the original object. Therefore, the magnifying power $m$ is indeed negative. Assertion (A) is True.
• Analysis of Reason (R): As established, the final image formed by a compound microscope is inverted, not erect, with respect to the object. Reason (R) is False.

Step 3 (Final Concluded Answer): [0.25 Mark]

Correct Option: Assertion (A) is true, but Reason (R) is false.

💡 EL10 Concept Insight: Think of a compound microscope like a two-step mirror game: the first lens flips the image upside down, and the second lens just makes that upside-down image bigger, so the final result stays upside down (inverted).