⇒Pf1=f11+f21=f1f2f1+f2
Two thin lenses of focal lengths f1 and f2 are in contact and coaxial. The power of the combinations is
Held on 30 Apr 2008 · Verified 9 Jul 2026.
f1f2f1+f2
f2f1
f1f2
2f1+f2
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The refractive index of glass is 1.5. The speed of light in glass is:
Two thin lenses of focal lengths f₁ = +20 cm and f₂ = -10 cm are in contact. The power of the combination is:
An unpolarized light beam travelling in air is incident on a medium of refractive index 1.73 at Brewster's angle. Then -
A microscope has an objective of focal length 2 cm , eyepiece of focal length 4 cm and the tube length of 40 cm . If the distance of distinct vision of eye is 25 cm , the magnification in the microscope is :
The intensity of transmitted light when a polaroid sheet, placed between two crossed polaroids at $22.5^{\circ}$ from the polarization axis of one of the polaroid, is ( $\mathrm{I}_0$ is the intensity of polarised light after passing through the first polaroid):
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