4. What type of electromagnetic waves does a computer scanner use? Explain how the photoelectric effect is an important part of this process. (2 points)

Could someone me find the answer to this problem.

When the magnetic domains in a material can be aligned, but eventually drift out of alignment, the material is

Under the action of a constant force an object accelerates at 7.8 m/s2. what will the acceleration be if (a) the force is halved? (b) the object's mass is halved? (c) the force and the object's mass are both halved? (d) the force is halved and the object's mass is doubled?