What are two ways electromagnetic waves are used in a home computer scanner? A.
An image is produced when a silicon chip releases electrons by the photoelectric effect.

B.
Visible light is reflected off an object and then captured by a charge-coupled device.
C.
X-rays shine on objects, and the rays either pass through or are absorbed by the objects.
D.
Red light shines on a black-and-white object, and light is reflected according to the pattern of black and white.

Scientists use laser range-finding to measure the distance to the moon with great accuracy. a brief laser pulse is fired at the moon, then the time interval is measured until the "echo" is seen by a telescope. a laser beam spreads out as it travels because it diffracts through a circular exit as it leaves the laser. in order for the reflected light to be bright enough to detect, the laser spot on the moon must be no more than 1.0 km in diameter. staying within this diameter is accomplished by using a special large-diameter laser. part a if λ = 540nm , what is the minimum diameter of the circular opening from which the laser beam emerges? the earth-moon distance is 384,000 km. express your answer to two significant figures and include the appropriate units.

Molten iron fills a mould, which has a volume of 200 cm cubed. calculate the volume when the iron cools and solidifies.

What is the role of the ocular lens?