How to state the relationship between manipulated variable and the responding variable

Aprotein molecule in an electrophoresis gel has a negative charge. the exact charge depends on the ph of the solution, but 30 excess electrons is typical. what is the magnitude of the electric force on a protein with this charge in a 1600n/c electric field? write in two significant numbers, and also in newton

Acamcorder has a power rating of 20 watts. if the output voltage from its battery is 9 volts, what current does it use?

The dominant wavelength of energy emitted by the sun is