A convex mirror of focal length 10cm is kept at a distance of 30cm front of a 4cm high object.Find the height of the image of the object?

1 Answer
May 11, 2018

#"the length of the image is 1 cm."#

Explanation:

#-1/f=1/u-1/(u')#

#"where f is the focal length, u is the distance between the object and the mirror, "#u'#" is the distance from the image to the mirror."#

#"Since the focus and the image are behind the mirror, their signs is negative."#

  • Convex mirrors create a virtual image.
  • The image is smaller than the object.

#f=10" " cm#
#u=30" "cm#
#"let us calculate the image length using formula."#

#-1/10=1/30-1/(u^')#

#1/(u^')=1/10+1/30#

#1/(u^')=(3+1)/30#

#1/(u^')=4/30#

#u^'=7.5" " cm#

#g/c=(u')/u#

#"where g is the length of the image, c is the length of the object."#

#g/4=(u^')/u#

#g/4=(7.5)/30#

#g/4=1/4#

#g=1 cm#