Tag: physics

Here $F=180 \ cm$ and $f=30 \ cm$
$\therefore $ Magnifying power M
$=\dfrac {F}{f}=\dfrac {180}{3}=60$

• The visible light spectrum is the section of the electromagnetic radiation spectrum that is visible to the human eye. 
• It ranges in wavelength from approximately 400 nanometers ($4 \times  10 ^{-7}$ m, which is violet) to 700 nm ($7 \times 10^{-7}$ m, which is red).
  
• Hence wavelengths are infinite
• Option D is the right answer

Cosmic rays, γ-rays, and X-rays are part of electromagnetic spectrum, while β-rays are emitted by radioactive elements. Hence β-rays is not electromagnetic waves.

Astronomical telescopes uses convex lenses which form real and inverted image of object at infinite distance.

Telescopes objective lenses have large apertures so that more number of light rays coming from object should enter and have greater resolution.

To get a magnified image of an object at infinity the image formed by objective lens will beat focus and if we want maximum magnification then the image formed by objective should be at focus of the eye piece.

simple microscope is placed between the optic center and the focus and the image is erect, virtual and magnified.

An astronomical telescope is an optical instrument which is used to see the magnified image of distant heavenly bodies. The final image formed by an astronomical telescope is always virtual, inverted and magnified.

For astronomical telescope
$\left| { v } _{ 1 } \right| ={ f } _{ o }$
$\left| { u } _{ 2 } \right| \le { f } _{ e }$
Probable answer would be (c) conceptually correct