Ask a Doubt
Request a call back

Join NOW to get access to exclusive study material for best results

CBSE Class 12-science Answered

Dear sir, when we use the formula m=D/u instead of using m=1+D/f for the magnification of a simple microscope please explain in detail.
Asked by modi72879 | 23 Feb, 2018, 09:50: PM
answered-by-expert Expert Answer
Both formulas are one and the same.
Magnification M is obtained from the formula, M = v / u; where v is the image-to-lens distance and u is object-to-lens system.
Here D is the normal distance of least vision of human eye and microscope is desigened to produce the magnified image at D.
 
Hence we get M = ( D / u ).
 
if we consider the lens formula and do liitle simplification we will get the other formula as follows
begin mathsize 12px style 1 over v minus 1 over u space equals space 1 over f a p p l y i n g space s i g n space c o n v e n t i o n comma space v space equals space minus D space a n d space u space i s space n e g a t i v e comma space w e space g e t space fraction numerator 1 over denominator negative D end fraction plus 1 over u equals 1 over f space M u l t i p l y space t h e space a b o v e space r e l a t i o n space b y space D space a n d space u s e space t h e space f o r m u l a space M space equals space D over u comma space w e space g e t space M space equals space 1 plus D over f end style
 
if we know the Object-to-lens distance u and assuming the normal distance of least vision D, we get magnification from M = ( D/u ) . Here we need not know the focal length of the lens.
 
if we know the focal length of lens f and assuming the normal distance of least vision D, we get magnification from M = 1 + ( D / f ) . Here we need not know the object-to-lens distance u.
 
Answered by Thiyagarajan K | 24 Feb, 2018, 02:14: PM

Concept Videos

Multiple Choice Questions Practice Test
Answered Unanswered My Questions My Answers
CBSE 12-science - Physics
solve option e
question image
Asked by dasrituparna1999 | 13 Apr, 2024, 06:56: AM
ANSWERED BY EXPERT ANSWERED BY EXPERT
CBSE 12-science - Physics
The number of moles in an elemental sample is just the ratio of the mass m to atomic mass 4. n= A The number of protons N, in an elemental sample is Z (atomic number) times the number of moles of Avogadro's number NA N=ZnN P A Copper has an atomic mass of 63.5 g/mole and 29 protons per atom. If such an atom were neutral, then it would have as many protons as electrons. If you remove electrons from a neutral state, then you get a net positive charge. Given a 54 gram ball of copper with a net charge of 2.2 µC, what fraction of the copper's electrons have been removed?
Asked by dasrituparna1999 | 12 Apr, 2024, 09:26: PM
ANSWERED BY EXPERT ANSWERED BY EXPERT
CBSE 12-science - Physics
which answer is correct and most appropriate with explanation
question image
Asked by mishrigupta19319 | 08 Apr, 2024, 06:28: PM
ANSWERED BY EXPERT ANSWERED BY EXPERT
CBSE 12-science - Physics
8212
question image
Asked by madhav9119887644 | 07 Apr, 2024, 08:10: PM
ANSWERED BY EXPERT ANSWERED BY EXPERT
CBSE 12-science - Physics
ans the questions wit reason
question image
Asked by mishrigupta19319 | 07 Apr, 2024, 11:23: AM
ANSWERED BY EXPERT ANSWERED BY EXPERT
CBSE 12-science - Physics
I don't know which concept and formula is used
question image
Asked by adityagalar2007 | 06 Apr, 2024, 01:06: PM
ANSWERED BY EXPERT ANSWERED BY EXPERT
CBSE 12-science - Physics
what is the mass of the bidy
question image
Asked by amlanmcob | 06 Apr, 2024, 12:27: PM
ANSWERED BY EXPERT ANSWERED BY EXPERT
CBSE 12-science - Physics
13./A point charge of 12 µC is located at the centre of a cube of side 1 m. Calculate the electric flux through each face of the cube. (H.S.S.C.E.1999~S) [Ans. 2.26\times10^{5}N~m^{2}C^{-1}]
Asked by hussain221man | 05 Apr, 2024, 08:44: PM
ANSWERED BY EXPERT ANSWERED BY EXPERT
CBSE 12-science - Physics
A coil of N turns is placed in a magnetic field B such that B is perpendicular to the plane of the coil. B changes with time as B=B0 cos 2元 where T is time period. The magnitude of emf-induced in the coil will be maximum at
question image
Asked by mishrigupta19319 | 05 Apr, 2024, 12:01: PM
ANSWERED BY EXPERT ANSWERED BY EXPERT
CBSE 12-science - Physics
a charge of 2microcoulomb experience a force of 6N when placed at a point in an electric field .find electric field at that point
Asked by manishamunda787 | 02 Apr, 2024, 11:07: AM
ANSWERED BY EXPERT ANSWERED BY EXPERT
My Class Videos Tests ₹ Plans Ask a Doubt
Get Latest Study Material for Academic year 24-25 Click here
×