1. The problem statement, all variables and given/known data A sphere of radius 12.0cm has refractive index of 1.33. A speck is 4.0cm from the centre of the sphere is viewed along the diameter that passes thru the speck. Find the position of image when the speck is viewed from the nearer side? the ans is -7.2cm 2. Relevant equations 3. The attempt at a solution n1= 1.33 n2= 1 , u = +0.08m. Assuming light travel form right to left , The nearer position from the speck to the left refracting surface is +0.08m. so this lead me to (1.33/0.08) +1/(v) = (1-0.33)/(-0.12) , my v is -0.05m . r is negative because the refracting surface is concave to the object. i just cant understand why I am wrong ? please help! p/s : the speck is inside the spherical (ball) am i right?