PF/PF-PB1 = P. Continue Reading. The image A 1 B 1 is formed at a distance 'v' from the mirror. Equation (2) becomes From equations (1) and (3) we get [PF = f, PB 1 = v, PB = u, PC = 2f] If The speed of light in vaccvum is 3×10 8.find the absolute refractive index of a medium in which light travels with a speed of 1.5× 10 8, http://www.ncert.nic.in/ncerts/textbook/textbook.htm?leph2=3-7, Sample papers, board papers and exam tips. In ABC and A1B1C