Focal Length of Convex Lens By Two Pin Method – Viva Voice | Physics Class 11

Download our Android App from Google Play Store and start reading Reference Notes Offline.

Convex LensViva Voice Questions With Answer
Focal Length of Convex Lens By Two Pin Method
For: Science Class 11 | Physics

Q.1: What is a lens?
Ans. A lens is a portion of a transparent medium bounded by two spherical surfaces or by one
spherical surface and a plane surface.

Q.2: How many principal foci are there for a lens?
Ans. Two, one on either side of the lens.

Q.3: What is the reference point for measuring p, q and f for a lens?
Ans. The optical centre of the lens.

Q.4: What kind of images are formed by convex lens?

Position of ObjectPosition of ImageRelative size of imageNature of image
1. at infinity
2. beyond C
3. at C
between C & F
5. at F
6. between F & O
at focus
between F & C
at ‘C’
beyond ‘C’
at infinity
behind the object
real; inverted
real; inverted
real; inverted
real; inverted
real; inverted
Virtual; erect

Q.5: What is the magnifying power (M) of a magnifying glass?
Ans. M = (1 + d/f ), where d = 25 cm = least distance of distinct vision.

Q.6: If the power of a convex lens is 0.1 diopter; what will be its focal length?
Ans. P = 1/f, so that, f = 1/p = 1/0.1 = 10m

Q.7: Which defect is present in lenses but not in mirrors?
Ans. Chromatic aberration.

Q.8: What are uses of lenses?
Ans. Combination of lenses are used in microscopes, telescopes, projectors, binoculars, cameras, etc.

Q.9: What is lens maker’s formula?
Ans. 1/f = (n – 1) (1/R1 – 1/R2)

f = focal length of the lens.
n = refractive index of the glass used for making the lens.
R1 = Radius of curvature of one surface.
R2 = Radius of curvature of the other surface.

Posted By : MeroSpark | Comment RSS | Category : Practical Exam, Viva Voice
Tag : , ,

One Comment

  1. Faizan Rajaa
    Posted September 28, 2016 at 9:37 pm

    it is very useful

Post a Comment

Your email is never published nor shared. Required fields are marked *