A vibrating string goes back and forth 412 times in 3 minutes. Find the frequency and period of the string.

With i really need the correct answer!

Starting with only the balmer series light (visible light), how could we ensure that the solar panels generate a current that mark can use for his power station? a)by gradually increasing the brightness (amount) of light that we shine on it. b)by gradually increasing the frequency of the light we shine on it. c)by gradually increasing the wavelength of the light that we shine on it.

Simple machines can a. increase force only b. decrease force only c. increase or decrease force