What statement is true about the part of the electromagnetic spectrum that is visible to the human eye? a. it is divided into nine ranges of wavelengths b. it is made up of three types of electromagnetic spectrum c. it is made up of two types of electromagnetic spectrum d. it is divided into seven ranges of wavelengths

Based on the options above, I see how the last option would actually be most fitting to how "the part of the electromagnetic spectrum that is visible to the human eye". This would be in separate parts, which would be divided into a certain number, which would actually be only 7 ranges of wavelengths. And therefore, this last statement would actually go very well and it would actually be the correct answer. And this would all relate to how  the part of the electromagnetic spectrum that is visible to the human eye, it's based on it's own 7 division parts that it has. 

Your  

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

F  you double the  force, you double the acceleration, but  if  you double the  mass, you velocity. all bodies accelerate at the  same  rate regardless of size or  mass.