Diameter of the objective of a telescope is 200 cm. What is the resolving power of a telescope? Take wavelength of light=5000Å.

Options

(a) 6.56×10⁶
(b) 3.28×10⁵
(c) 1×10⁶
(d) 3.28×10⁶

Correct Answer:

3.28×10⁶

Explanation:

Given, wavelength of light, λ = 5000Å = 5000 × 10⁻¹⁰ = 5 × 10⁻⁷ m

Diameter of telescope, D = 200 cm = 2 m

Resolving power of a telescope = 1 / dθ = D / 1.22λ

where, dθ = limit of resolution, λ = wavelength of light used and D = diameter of aperture of objective

So, Resolving power = 2 / (1.22 × 5 × 10⁻⁷)

= 2 × 10⁷ / 6.1

= 3.278 × 10⁶

= 3.28 × 10⁶