Question

If astronomical telescope of length 1.53 m has magnifying power of magnitude 50, the values of f_o and f_e are ____________.

Options

• f_o = 0.03 m, f_e = 1.5 m

• f_o = 1.55 m, f_e = -0.02 m

• f_o = 1.5 m, f_e = -0.03 m

• f_o = 1.5 m, f_e = 0.03 m

Answer 1

If astronomical telescope of length 1.53 m has magnifying power of magnitude 50, the values of f_o and f_e are f_o = 1.5 m, f_e = 0.03 m.

Explanation:

`"L" = "f"_"o" + "f"_"e" = 1.53 "m"`    .....(i)

`abs("M.P") = "f"_"o"/"f"_"e" = 50`

`50  "f"_"e"+ "f"_"e" = 1.53`

`51  "f"_"e" = 1.53`

`therefore  "f"_"e" = 0.03  "m" `

From equation (i),

`"f"_"o" = 1.5  "m"`

`therefore  "f"_"o" = 1.5  "m and"  "f"_"e" = 0.0.3  "m"`