Answer:The height of the image is -6 mm.
Explanation;
Distance of the object form the lens = u = 12 mm
Distance of the image formed from the lens = v = 4 mm
Height of the object = 18 mm=\(h_o\)
The magnification is given by :
\(M=-\frac{v}{u}=\frac{h_i}{h_o}\)
\(h_i\& h_o\)= Height of an image and object respectively.
\(M=-\frac{4 mm}{12 mm}=\frac{h_i}{18 mm}\)
\(h_i=-6 mm\)
The height of the image is -6 mm.The image formed is real and negative sign signifies that image is inverted.
