MCQ
Magnification produced by astronomical telescope for normal adjustment is $10$ and length of telescope is $1.1\, m$. The magnification when the image is formed at least distance of distinct vision $(D = 25\, cm)$ is
- ✓$14$
- B$6$
- C$16$
- D$18$
✓
Answer
Correct option: A.
$14$
a
$f_{0} / f_{e}=10, \quad f_{\circ}+f_{e}=1.1$
$f_{0} / f_{e}=10, \quad f_{\circ}+f_{e}=1.1$
here $f_{\circ}=100 \mathrm{\,cm}$ and $f_{\mathrm{e}}=10 \mathrm{\,cm}$
Final magnification $=f_{\circ}\left(\frac{1}{D}+\frac{1}{f_{e}}\right)=14$
Need a full question paper?
Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.
Explore more
Similar questions
A pendulum clock keeps correct time at $0°C$. Its mean coefficient of linear expansions is $\alpha /^\circ C$, then the loss in seconds per day by the clock if the temperature rises by $t°C$ is
→One end of a spring of force constant k is fixed to a vertical wall and the other to a block of mass m resting on a smooth horizontal surface. There is another wall at a distance ${x_0}$ from the black. The spring is then compressed by $2{x_0}$ and released. The time taken to strike the wall is
→The Young's modulus of the material of a wire is $6 \times {10^{12}}\,N/{m^2}$ and there is no transverse strain in it, then its modulus of rigidity will be
→Two light waves of wavelengths $800$ and $600\,nm$ are used in Young's double slit experiment to obtain interference fringes on a screen placed $7\,m$ away from plane of slits. If the two slits are separated by $0.35\,mm$, then shortest distance from the central bright maximum to the point where the bright fringes of the two wavelength coincide will be $.............mm$.
→Three right angled prisms of refractive indices ${n_1},{n_2}$ and ${n_3}$ are fixed together using an optical glue as shown in figure. If a ray passes through the prisms without suffering any deviation, then
→A step-up transformer operates on $220 \,V$ line and supplies $2.2 \,A$. The ratio of primary and secondary winding is $11: 50$. The output voltage in the secondary is .......... $V$
→The temperature of a gas having $2.0 \times 10^{25}$ molecules per cubic meter at $1.38 \mathrm{~atm}$ (Given, $\mathrm{k}=$ $\left.1.38 \times 10^{-23} \mathrm{JK}^{-1}\right)$ is :
→What is the effect on Fresnel’s biprism experiment when the use of white light is made
Three concentric metallic spherical shells of radii $R, 2R, 3R$, are given charges $Q_1, Q_2, Q_3$, respectively. It is found that the surface charge densities on the outer surfaces of the shells are equal. Then, the ratio of the charges given to the shells, $Q_1 : Q_2 : Q_3$ is
→The effective capacitance between the points $P$ and $Q$ of the arrangement shown in the figure is......$\mu F$
→