An object 15 cm from a lens produces a real image 30 cm from the lens. What is the focal length of the lens?
Correct answer: C. +10 cm
- A. +15 cm
- B. +20 cm
- C. +10 cm
- D. +25 cm
Explanation
A real image can only be produced by a convex lensSo,v= +30 and u= -15The formula of the lens is 1/f=1/v-1/unow putting values1/f= 1/30-1/-151/f= 1/30+1/151/f = 3/30f= +10 cm.
Report an error
The more specific you are, the faster it gets fixed. A source beats an opinion.
Prefer email? [email protected]
About Optics
Light is studied through reflection, refraction, dispersion, interference, diffraction and polarization, linking ray behavior with its wave nature. Questions may involve mirrors, lenses, optical instruments, refractive index and image formation, while geometrical optics deals with rays and wave optics explains effects such as interference and diffraction.
Practise Optics
665 free Optics MCQs from Physics, each with the correct answer and an explanation. Unlimited attempts, no account needed.
Discussion
Stuck on an option, or know a faster way to get there? Ask or explain it here.
No comments yet. Be the first to explain this one.
Exams that ask Physics questions like this
Physics is on 11 papers prepared for on TestUstad, and all of them draw the same bank, so this question is worth knowing for every one of them.
More Optics questions
In the diffraction of light around an obstacle, the angle of diffraction is increased then:
The minimum distance from the eye at which an object can be seen clearly without strain is called:
The distance between atoms is 0.30 nm. What will be the wavelength of X-rays at an angle θ=30 for 1st-order diffraction?
What is the formula for critical angle in case of light through two media having refractive indices n1 and n2 such that n1 > n2?
Diffraction is the characteristic of:
In YDSE, if we use white light in place of monochromatic light, then the: