Need help with the following questions, I think I understand alb, and c but I don't know where to start with d Answer the following questions about Blu-ray laser:
(a) The laser on a Blu-ray player has a wavelength of 405nm. In what region of the electromagnetic spectrum is this radiation? What is its frequency?
(b) A Blu-ray laser has a power of 5 milliwatts (1 watt= 1Js-1). How many photons of light are produced by the laser in 1 hour?
(c) The ideal resolution of a player using a laser (such as a Blu-ray player), which determines how close together data can be stored on a compact disk, is determined using the following formula: Resolution= 0.60(/NA), where  is the wavelength of the laser and NA is the numerical aperture. Numerical aperture is a measure of the size of the spot of light on the disk; the larger the NA, the smaller the spot. In a typical Blu-ray system, NA=0.95. If the 405-nm laser is used in a Blu-ray player, what is the closest that information can be stored on a Blu-ray disk?

(d) The data density of a Blu-ray disk using a 405-nm laser is 1.5x107 bits nm-2. Disks have an outside diameter of 120nm and a hole of 15-nm diameter. How many data bits can be contained on the disk? If a Blu-ray disk can hold 9,400,000 pages of text, how many data bits are needed for a typed page? (hint: determine the area of the disk that is available to hold data. The area inside a circle is given by A=r2, where the radius r is one-half of the diameter.)