| PULSAR | Rotating star that emits beams of electromagnetic radiation (6) |
| PHOTON | A quantum of electromagnetic radiation (6) |
| QUASAR | Name a source of electromagnetic radiation (6) |
| PHOSPHOR | General term for a substance, such as the coating on a cathode-ray tube, that emits light when irradiated with particles of electromagnetic radiation (8) |
| COLOUR | Any one of the spectral hues determined by ocular interpretation of electromagnetic waves whose principles can be demonstrated by means of a Newton disc (6) |
| LASERS | Devices that emit narrow beams of monochromatic light continuously or in pulses (6) |
| BURNER | Part of an etna, gas cooker/jet or lamp etc that emits a flame; a censer or thurible; or, a CD-R drive (6) |
| OPTICS | The branch of science concerned with vision and the behaviour of electromagnetic light (6) |
| STARLIGHT | Form of electromagnetic radiation emitted by luminous celestial bodies in the observable universe that have radiated some 4x1084 photons since the beginning of time (9) |
| ANGSTROM | Unit of length equal to one tenth of a nanometre, chiefly used to express wavelengths of electromagnetic radiation (8) |
| ULTRA | Word that links with "violet" for a form of electromagnetic radiation (5) |
| SPECTRA | Characteristic series of frequencies of electromagnetic radiation substances emit |
| SPECTRUM | Range of electromagnetic radiation, that includes visible light (8) |
| XRAYED | Examined using electromagnetic radiation of short wavelength (1-5) |
| CICADA | Insect that emits a whistle |
| SKUNKS | Animals that emit foul smells (6) |
| SUNLIGHT | Providing humans with vitamin D and triggering the release of serotonin and melatonin in the brain, a natural form of electromagnetic radiation (8) |
| SPEEDOFLIGHT | A fundamental constant of nature and physics defined by the vacuum propagation rate of electromagnetic radiation, exactly 299,792,458 metres per second (5,2,5) |
| XRAYTUBES | Generators of electromagnetic radiation used in hospitals |
| PHOTONS | Smallest possible units of electromagnetic radiation (7) |
