1.a wave has a period of 20 seconds. what is the frequency?

2.in 4 seconds 3 waves pass a point. what is the frequency? what is the period?

3.what is the speed of a wave that has a frequency of 2hz, an amplitude of 10m, and a wave length of 5m?

When a vertical beam of light passes through a transparent medium, the rate at which its intensity i decreases is proportional to i(t), where t represents the thickness of the medium (in feet). in clear seawater, the intensity 3 feet below the surface is 25% of the initial intensity i0 of the incident beam. what is the intensity of the beam "10" feet below the surface? (give your answer in terms of i0. round any constants or coefficients to five decimal places.)