# JEE Main & Advanced Physics Ray Optics Astronomical Telescope (Refracting Type)

Astronomical Telescope (Refracting Type)

Category : JEE Main & Advanced

By astronomical telescope heavenly bodies are seen.

(1) ${{f}_{\text{objective}}}>{{f}_{\text{eyelens}}}$and ${{d}_{\text{objective}}}>{{d}_{\text{eye lens}}}$.

(2) Intermediate image is real, inverted and small.

(3) Final image is virtual, inverted and small.

(4) Magnification :  ${{m}_{D}}=-\frac{{{f}_{0}}}{{{f}_{e}}}\left( 1+\frac{{{f}_{e}}}{D} \right)$ and ${{m}_{\infty }}=-\frac{{{f}_{o}}}{{{f}_{e}}}$

(5) Length : ${{L}_{D}}={{f}_{0}}+{{u}_{e}}$ and ${{L}_{\infty }}={{f}_{0}}+{{f}_{e}}$

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