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Question:

Diameter of the objective lens of a telescope is 250cm. For light of wavelength 600nm. coming from a distant object, the limit of resolution of the telescope is close to?

2.0×10⁻⁷rad

1.5×10⁻⁷rad

4.5×10⁻⁷rad

3.0×10⁻⁷rad

Solution:

Correct option is C. 3.0×10⁻⁷rad
Limit of resolution = 1.22λ/d = 1.22 × 600 × 10⁻⁹ / 250 × 10⁻² = 2.9 × 10⁻⁷rad.