Alens system has a back vertex power of +5.00 d, a neutralizing power of +4.00 d, and an equivalent power of +10.00 d. the back surface is in water and the front surface is in air. locate the six cardinal points this means when parallel light comes in power leaving back focus @f. we use it to find back vertex to secondary focal ph- remember n 1.33 is +5 and wil fr .fe-nya. -lu /woo : t400 d low) ^+" ; l. syカ0いこ+0-8 3 m ,ire -0.1or 0.133 n: 0.033 l: 10-133 pn t0.033 p t. 033m

Answer: a charge of -1.0  × 10⁻⁴ c must be placed  at x = 26 m.the sign of the charge will be the same sign as the  -4.0  µc charge.======electricstatic force between two point charges  is given by    where k is coulomb's constant,  8.99×10⁹  n·m²/c², q₁ and q₂ are the point charges, and r is the distance between the two point charges.assign positive to q₁let q₁ =  6.0 µc, q₂ = -4.0  µc, q₀ represent the charge at the origin, and q₃ represent this new charge to place.the charge at the origin q₀ would experience the following force f₀₁ from q₁, with r = 6.0 m (note that 1  µc = 10⁻⁶ c)    the force from q₂    the force from q₃    the net force on the origin charge, q₀, has to be zero for no electrostatic forcehaving an equation where k and q₀ can be divided out of the equation will allow us to solve for q₃    isolating:     a charge of -1.0  × 10⁻⁴ c must be placed  at x = 26 m.the sign of the charge will be the same as the  -4.0  µc charge