The energy of electromagnetic waves increases with decreasing wavelength. Which of the following statements support this claim?
O A. Dental patients need to wear lead aprons to protect themselves from X-rays but do not wear
protection from flashlights.
B. Both radio waves and gamma rays are invisible to human eyes.
C. Ultraviolet radiation causes sunburn but radio waves do not.
D. Microwaves are used for communication.
E. Gamma rays are used to kill cancer cells, but microwaves have no known effect on cancer
cells.

Cyclotrons are widely used in nuclear medicine for producing short-lived radioactive isotopes. these cyclotrons typically accelerate h- (the hydride ion, which has one proton and two electrons) to an energy of 5 mev to 20 mev. this ion has a mass very close to that of a proton because the electron mass is negligible—about 1 2000 of the proton’s mass. a typical magnetic field in such cyclotrons is 1.9 t. (a) what is the speed of a 5.0-mev h-? (b) if the h- has energy 5.0 mev and b = 1.9 t, what is the radius of this ion’s circular orbit?