An object is placed at a distance of 40 cm in front of a concave mirror of focal length 20 cm. The image produced is

Options

A. real and inverted and of same size
B. virtual and erect and of same size
C. real and erect and of samee size
D. virtual and inverted and of same size

Answer

A

Explanation

According to new cartesian sign convention,

Object distance u=-40cm
Image distance v=?
focal length f=-20cm
`therefore`From mirror formula
`(1)/(v)+(1)/(u)=(1)/(f)`
or `(1)/(v)=(1)/(f)-(1)/(u)`
or `(1)/(v)=(1)/(-20)-(1)/((-40))=-(1)/(40)`
or `v=-40cm`
`therefore` The image is on the same side of the object.
Now, magniffication
`m=-(v)/(u)=-((-40))/((-40))=-1`
Hence, the image is real, inverted and of same size.