Variable What is the variable How will it be used Independently variable amount of salt (NaCl) The amount of salt will change by 1g each time up to a maximum of 5 g Variable angle dependent on refraction It will be measured by drawing on the line of incidence and the line of refraction and measuring the angle of refraction Variable controlled Same angle of incidence I will draw the angle d 'incidence 5 times and it will be in the exact same place on each paper Same Light I will use the same light box and power source to keep the experiment controlled. Same medium Instead of changing the water every time, I will increase and dissolve an extra gram of salt each time. Required equipment and materials: BalanceMeasuring cylinderRadius