A boy of height 1.5m with his eye level at 1.4m stands before a plane mirror of length 0.75 m fixed on the wall. The height of the lower edge of the mirror above the floor is 0.8 m. Then ,

Options

A. the boy will see his full image
B. the boy cannot see his hair
C. the boy cannot see his feet
D. the boy can see neither his hair nor his feet

Answer

C

Explanation

` ( d + x ) /( 0 .8 ) = ( 2d + x ) /( 1.4 ) ` (By similar triangle )
`rArr 1.4 d + 1.4 x = 1.6 d = 0.8 x rArr x = ( d ) / ( 3 ) `
` therefore ` By similar triangles,
` ( x ) /( h ) = ( x + d ) /( 0 .8 ) `
` ( d ) /( 3h ) = ( 4d ) /( 2.4 ) `
` h + (2.4 ) /( 3xx 4 ) = 0.2 m `
Hence the person cannot see his feet.