2025 - JAMB Physics Past Questions and Answers - page 10

The International System of Units consists of seven fundamental units from which all other units are derived. The ampere is one of these fundamental units and is used to measure electric current. Other options listed, such as joule, volt, and ohm, are derived units formed from combinations of base units. Therefore, the correct base unit among the options is the ampere.

Electromagnetic waves differ in wavelength and frequency. Waves with shorter wavelengths have higher frequencies and energies. The order from shortest to longest wavelength is gamma rays, X-rays, ultraviolet radiation, visible light, infrared radiation, microwaves, and radio waves. Comparing the given options, X-rays have a shorter wavelength than ultraviolet radiation, visible light, and infrared radiation. Therefore, X-rays have the shortest wavelength among the listed options.