20 cm high object is placed at a distance of 25 cm from a converging lens of focal length of 10 cm . Determine the position , size and type of the image .

Explanation

Date: Converging lens, f= 10 , u =-25 cm `h_1 =5 cm` v=? `h_2 = ? `
(i) `1/f = 1/v-1/u :. 1/ v= 1/f + 1/u`
`:. 1/v = 1/(10 cm) + 1/(-25 cm ) = 1/(10 cm )-1/(25 cm ) `
`= (5-2)/( 50 cm ) =3/(50 cm ) `
`:.` Image distance ,` v = 50 / 3 cm `
` div 16.67 cm div 16.7 cm ` This gives the position of the image.
(ii) ` h_2 /h_1 = v/ u :. h_2 = v/u h_1 `
` therefore h_2 =((50/3) cm )/(-25 CM ) xx 20 cm =- ( 50 xx 20)/(25 xx 3) cm`
`=- 40/3 cm div - 13.333 cm `
` div - 13.3 ` cm
The height of the image =- 13.3 cm ( inverted image ) `
` therefore ` minus sign .
(iii) The image is real , invreted and smaller than the object .