Question:
In a telescope the objective has much larger aperture than the eye piece. Why ?
In a telescope the objective has much larger aperture than the eye piece. Why ?
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Paraboloidal mirrors are preferred in reflecting telescopes over spherical mirrors to eliminate spherical aberration completely without needing corrective lenses.
Updated On: Sep 14, 2026
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Solution and Explanation
Concept:
• Objective lens collects light from faint, distant astronomical bodies.
• Light gathering power is proportional to area of aperture ($\propto D^2$).
• Resolving power is given by $R.P. = \frac{D}{1.22 \lambda}$.
Step 1: Reason for Large Aperture Objective
1. Light Gathering Power: Distant stars/galaxies emit extremely faint light. A large aperture objective lens collects a large quantity of light rays, forming bright and clear images.
2. Resolving Power: Resolving power of telescope is directly proportional to diameter $D$ of objective aperture ($R.P. = \frac{D}{1.22 \lambda}$). A larger aperture enables resolving close double stars or fine details of celestial bodies.
Step 2: Conclusion
Large objective aperture maximizes light collection and spatial resolution. Reflecting telescopes overcome chromatic aberration and structural weight constraints inherent to refracting lens systems.
• Objective lens collects light from faint, distant astronomical bodies.
• Light gathering power is proportional to area of aperture ($\propto D^2$).
• Resolving power is given by $R.P. = \frac{D}{1.22 \lambda}$.
Step 1: Reason for Large Aperture Objective
1. Light Gathering Power: Distant stars/galaxies emit extremely faint light. A large aperture objective lens collects a large quantity of light rays, forming bright and clear images.
2. Resolving Power: Resolving power of telescope is directly proportional to diameter $D$ of objective aperture ($R.P. = \frac{D}{1.22 \lambda}$). A larger aperture enables resolving close double stars or fine details of celestial bodies.
Step 2: Conclusion
Large objective aperture maximizes light collection and spatial resolution. Reflecting telescopes overcome chromatic aberration and structural weight constraints inherent to refracting lens systems.
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