MCQ
High magnifying power microscopes have oil-immersion objectives
  • A
    to increase the fringe width
  • to increase the numerical aperture of the objective
  • C
    to decrease the wavelength of light
  • D
    because oil does not damage the observed sample.

Answer

Correct option: B.
to increase the numerical aperture of the objective
to increase the numerical aperture of the objective

Need a full question paper?

Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.

Start Generating Free

Similar questions

The unit of coefficient of viscosity is
A magnetic field of $2 \times 10^{-2} T$ acts right angles to a coil of area $100 cm ^2$ with 50 turns. The average e.m.f. induced in the coil is $0.1 V$, when it is removed from the field in time ' $t$ '. The value of ' $t$ ' is
The ratio of areas of the circular orbit of an electron in the ground state to that of the first excited state of an electron in a hydrogen atom is ______  
Light of wavelength $\lambda$ which is less than threshold wavelength is incident on a photosensitive material. If incident wavelength is decreased so that emitted photoelectrons are moving with some velocity then stopping potential will
A proton enters a perpendicular uniform magnetic field B at origin along the positive x axis with a velocity v as shown in the figure. Then it will follow the following path. [The magnetic field is directed into the paper].

Image

The force acting on the electron in hydrogen atom (Bohr' theory) is related to the principal quantum number ' $n$ ' as
A circular loop of radius 0.0157 m carries a current 2 A. The magnetic field at the centre of the loop is ______  
A cord is wound around the circumference of wheel of radius ' $r$ '. The axis of the wheel is horizontal and moment of inertia about it is ' $r$. The weight ' $m g$ ' is attached to the end of the cord and falls from rest. After falling through a distance ' $h$ ', the angular velocity of the wheel will be
An alternating electric field of frequency ' $u$ ' is applied across the dees (radius $R$ ) of a cyclotron to accelerate protons (mass $m$ ). The operating magnetic field ' $B$ ' used and K.E. of the proton beam produced by it are respectively ( $e=$ charge on proton)
Four resistances 4 Ω, 8Ω, XΩ and 12Ω are connected in a series to form Wheatstone’s network. If the network is balanced, the value of X is ______.