https://www.khanacademy.org/science/ms-physics/x1baed5db7c1bb50b:waves/x1baed5db7c1bb50b:electromagnetic-waves/v/the-electromagnetic-spectrum 2025-07-01T10:10:08.145512912Z The electromagnetic spectrum Light is an electromagnetic wave. All electromagnetic waves travel at the speed of light in vacuum. The frequency of a light wave corresponds to its color. The amplitude of a light wave corresponds to its brightness. Visible light is only a small part of the electromagnetic spectrum, which also includes radio, microwaves, infrared, ultraviolet, X-rays, and gamma rays. These different frequencies of electromagnetic waves have different applications. Mahesh Shenoy video https://cdn.kastatic.org/ka_thumbnails_cache/e317d099-29e7-41b4-a05c-8f7178545f8b_1280_720_base.png The electromagnetic spectrum Light is an electromagnetic wave. All electromagnetic waves travel at the speed of light in vacuum. The frequency of a light wave corresponds to its color. The amplitude of a light wave corresponds to its brightness. Visible light is only a small part of the electromagnetic spectrum, which also includes radio, microwaves, infrared, ultraviolet, X-rays, and gamma rays. These different frequencies of electromagnetic waves have different applications. https://cdn.kastatic.org/ka-youtube-converted/iVbuCROYAz4.mp4/iVbuCROYAz4.mp4 523 Electromagnetic waves https://www.khanacademy.org/science/cambridge-o-level-physics-cie/x0e04e0cb682fb793:electromagnetic-spectrum/x0e04e0cb682fb793:untitled-526/v/electromagnetic-waves-and-matter 2025-07-01T10:10:08.145512912Z Electromagnetic waves and matter Electromagnetic (light) waves travel along straight line paths. We can model these paths using rays. When a light ray encounters a boundary between different materials, the light can be reflected, absorbed, and/or transmitted. Most everyday objects don't emit their own visible light. We see these objects when visible light from a source reflects off of the object and into our eyes. Objects that absorb all colors of visible light appear black. Mahesh Shenoy video https://cdn.kastatic.org/ka_thumbnails_cache/732a6dc9-a8b8-46dd-81e7-022521e69b88_1280_720_base.png Electromagnetic waves and matter Electromagnetic (light) waves travel along straight line paths. We can model these paths using rays. When a light ray encounters a boundary between different materials, the light can be reflected, absorbed, and/or transmitted. Most everyday objects don't emit their own visible light. We see these objects when visible light from a source reflects off of the object and into our eyes. Objects that absorb all colors of visible light appear black. https://cdn.kastatic.org/ka-youtube-converted/nXuPL8KD2SU.mp4/nXuPL8KD2SU.mp4 456 Electromagnetic waves https://www.khanacademy.org/science/cambridge-o-level-physics-cie/x0e04e0cb682fb793:electromagnetic-spectrum/x0e04e0cb682fb793:untitled-526/a/electromagnetic-waves 2026-06-16T04:23:47.092153677Z Learn and try: Electromagnetic waves Learn about electromagnetic waves, including visible light waves. Explore the ray model and use it to model different behaviors of light. article https://www.khanacademy.org/science/cambridge-o-level-physics-cie/x0e04e0cb682fb793:electromagnetic-spectrum/x0e04e0cb682fb793:untitled-526/e/understand-absorption-and-reflection 2026-05-01T13:40:34.883034315Z Understand: Electromagnetic waves Check your understanding of electromagnetic waves in this set of free, standards-aligned practice questions. Khan Academy exercise https://www.khanacademy.org/science/ms-physics/x1baed5db7c1bb50b:waves/x1baed5db7c1bb50b:electromagnetic-waves/e/apply-absorption-and-reflection 2026-05-01T13:40:34.883034315Z Apply: Electromagnetic waves Apply your knowledge of electromagnetic waves in this set of free, standards-aligned practice questions. Khan Academy exercise https://www.khanacademy.org/science/cambridge-o-level-physics-cie/x0e04e0cb682fb793:general-properties-of-waves/x0e04e0cb682fb793:refraction-of-light-waves/v/refraction_of_light 2024-05-20T12:23:45.127797789Z Refraction of light Light refracts—it bends—when it passes from one medium into another at an angle. Refraction occurs because the phase velocity of light is different in different media. For example, light slows down when it passes from air into glass. This happens because the incoming electromagnetic wave causes electrons in the medium to oscillate, which produces a secondary electromagnetic wave. The resulting wave, which is a superposition of the incoming wave and the secondary wave, has a different phase velocity than c. Mahesh Shenoy video https://cdn.kastatic.org/ka_thumbnails_cache/2202cd4e-288c-42cd-ae56-014a4b58dc42_1280_720_base.png Refraction of light Light refracts—it bends—when it passes from one medium into another at an angle. Refraction occurs because the phase velocity of light is different in different media. For example, light slows down when it passes from air into glass. This happens because the incoming electromagnetic wave causes electrons in the medium to oscillate, which produces a secondary electromagnetic wave. The resulting wave, which is a superposition of the incoming wave and the secondary wave, has a different phase velocity than c. https://cdn.kastatic.org/ka-youtube-converted/LKI1UmFbfaA.mp4/LKI1UmFbfaA.mp4 872 Electromagnetic waves https://www.khanacademy.org/science/cambridge-o-level-physics-cie/x0e04e0cb682fb793:general-properties-of-waves/x0e04e0cb682fb793:wave-inetrference-and-diffraction/v/diffraction_and_interference_of_light 2024-05-27T18:30:38.024551145Z Diffraction and interference of light Light spreads out when it encounters an obstacle. This process is called diffraction. Diffraction is most noticeable when the obstacle is similar in size to the wavelength of the light. When light waves diffract around obstacles, they overlap each other. This overlap results in constructive and destructive interference at different locations, producing an interference pattern. Mahesh Shenoy video https://cdn.kastatic.org/ka_thumbnails_cache/0a396635-facb-4763-a911-78011f2e65af_1280_720_base.png Diffraction and interference of light Light spreads out when it encounters an obstacle. This process is called diffraction. Diffraction is most noticeable when the obstacle is similar in size to the wavelength of the light. When light waves diffract around obstacles, they overlap each other. This overlap results in constructive and destructive interference at different locations, producing an interference pattern. https://cdn.kastatic.org/ka-youtube-converted/VmN3i4HW5l0.mp4/VmN3i4HW5l0.mp4 878 Electromagnetic waves https://www.khanacademy.org/science/cambridge-o-level-physics-cie/x0e04e0cb682fb793:general-properties-of-waves/x0e04e0cb682fb793:wave-inetrference-and-diffraction/e/apply-refraction-diffraction-and-interference-of-light 2026-06-29T18:00:57.756067884Z Apply: Refraction, diffraction, and interference of light Apply your knowledge of refraction, diffraction, and interference of light in this set of free practice exercises. Emily Cizmas exercise