Question: The intermediate image formed in a compound microscope is:
Step 1 (Governing Principle & Optical Setup): [0.5 Mark]
In a compound microscope, the objective lens ($L_o$) is a convex lens of short focal length ($f_o$). The object is placed just beyond the focus ($f_o < u_o < 2f_o$). According to the lens formula:
$$\frac{1}{f_o} = \frac{1}{v_o} - \frac{1}{u_o}$$The objective lens forms the intermediate image ($I_1$) of the object. Since the object is placed outside the focal point of the objective lens, the lens acts as a real image projector.
Step 2 (Step-by-Step Optical Analysis): [0.25 Mark]
- Nature: Because the light rays actually converge at the image position, the image is real.
- Orientation: For a single convex lens, a real image formed by a real object is always inverted with respect to the object.
- Size: Since the object is placed close to the focus ($u_o \approx f_o$), the magnification $m_o = \frac{v_o}{u_o}$ results in a magnified image.
Step 3 (Final Concluded Answer): [0.25 Mark]
Based on the optical properties derived above, the intermediate image is real, inverted, and magnified.
Correct Option: (A)
💡 EL10 Concept Insight: Think of the objective lens like a projector lens; it takes the tiny object and flips it upside down while stretching it out to make it bigger, creating a "real" image that you could actually catch on a screen if you placed one inside the microscope tube.