Which are examples of a medium?

Light from a sodium lamp passes through a diffraction grating that has 1000 slits per millimeter. the interference pattern is viewed on a screen 1.000 m behind the grating. the first (m = 1) two bright yellow fringes that are visible are 0.7288 m and 0.7300 m from the central maximum. what are the wavelengths of these two fringes?

Avehicle accelerates from 0 to 30 m/s in 10 seconds on a straight road

3. a particle with initial velocity v⃗ 0=(5.85×103m/s)j^ enters a region of uniform electric and magnetic fields. the magnetic field in the region is b⃗ =−(1.35t)k^. you can ignore the weight of the particle. a. calculate the magnitude of the electric field in the region if the particle is to pass through undeflected, for a particle of charge +0.640 nc.