Saved Bookmarks
| 1. |
(a) With the help pf a ray diagram , show how a concavemirror is used to obtain an erect and magnified image of an object .(b)Using the ray diagram below , obtain the mirror formula and the expression for linear magnification. |
Answer» Solution :(a) (b)`DELTAA'B'P~DeltaABP`(by A Asimilarity) So ,`(A'B')/(AB)=(B'P)/(BP)=(+V)/(-U)` . . . (i) `DeltaA'B'C~DeltaABC`(by A A similarity) So ,`(A'B')/(AB)=(CB')/(CB)=(CP+PB')/(CP-BP)=(-2f+v)/(-2f-(-u))` . . . (ii) From equation (i)and (ii), `(+v)/(-u)=(-2f+v)/(-2f+u)` `v(-2f+u)=-(-2f+v)` `-2vf+4v=+2uf-uv` `2uv=2uf+2vf` Dividing by 2uvf, `(1)/(f)=(1)/(v)+(1)/(u)` From equation (i) , `(A'B')/(AB)=(-v)/(u)` So,`(h_("i"))/(h_(0))=(-v)/(u)` So,`m=(h_("i"))/(h_(0))=(-v)/(u)` |
|