physics hw help please?

1. A beam of polarized light of intensity I0 passes through a sheet of polarizing material. The polarization axis of the beam and filter differ by 30 degrees. What is the intensity of the emerging light?

a. 0.87 I0

b. 0.75 I0

c. 0.50 I0

d. 0.25 I0

2. You discover an old laser in your lab that you would like to use for an upcoming experiment, but its wavelength is unknown. To measure it, you direct the laser beam at a double-slit setup with a slit separation of 0.155 mm. You project the resulting interference pattern on a wall 2.14 m away. The first bright fringe is located 0.00876 m from the central bright fringe. Find the wavelength of the laser in nanometers.