An opera glass (Galilean telescope) measures 9 cm from the objective to the eyepiece. The focal length of the objective is 15 cm. Its magnifying power is

Question

An opera glass (Galilean telescope) measures 9 cm from the objective to the eyepiece. The focal length of the objective is 15 cm. Its magnifying power is (A) 2.5 (B) 2/5 (C) 5/3 (D) 0.4

Tardigrade Admin · Accepted Answer

fo-fe=9 cm and fe=fo-9=15-9=6 cm ⇒ m=(fe/fe)=(15/6)=2.5

Q. An opera glass (Galilean telescope) measures $9 c m$ from the objective to the eyepiece. The focal length of the objective is $15 c m$ . Its magnifying power is

2.5

2/5

5/3

0.4

$f_{o} - f_{e} = 9 c m$ and
$f_{e} = f_{o} - 9 = 15 - 9 = 6 c m$
$\Rightarrow m = \frac{f _{e}}{f _{e}} = \frac{15}{6} = 2.5$

Q. An opera glass (Galilean telescope) measures 9cm from the objective to the eyepiece. The focal length of the objective is 15cm. Its magnifying power is

2.5

2/5

5/3

0.4

fo​−fe​=9cm and fe​=fo​−9=15−9=6cm ⇒m=fe​fe​​=615​=2.5

Q. An opera glass (Galilean telescope) measures $9 c m$ from the objective to the eyepiece. The focal length of the objective is $15 c m$ . Its magnifying power is

$f_{o} - f_{e} = 9 c m$ and
$f_{e} = f_{o} - 9 = 15 - 9 = 6 c m$
$\Rightarrow m = \frac{f _{e}}{f _{e}} = \frac{15}{6} = 2.5$