a-b | c | d-f | g-j | k-m | n-p | r-s | t-z
Radiation the situation at high frequencies, where electric and magnetic fields are coupled together in a specific relationship so that they propagate through space carrying energy. Usually negligible at power frequencies
Radio frequencies Frequencies much higher than power frequencies, where radio and TV broadcasts and mobile phones operate
Radon A naturally occurring radioactive gas found in the air
Relative Risk How the result of an epidemiological study is often expressed. The ratio of the risk in the exposed group to the risk in the non-exposed group. An relative risk of 1 means there is no association between exposure and disease. Relative risk greater than 1 means the exposure is associated with the disease.
Revolt A UK campaign group with a strong interest in EMFs (Rural England Versus Overhead Line Transmission)
Right of Way (ROW) In the USA, the strip of land that a power line runs along. The power company usually have rights over the land to restrict certain sorts of use.
Risk Ratio Alternative term for relative risk
RMS or root mean square A measure used for AC quantities which allows them to be expressed as a single number. For practical purposes in the electricity industry, it is just a constant fraction of the amplitude: rms = 0.71 x amplitude, amplitude = 1.41 x rms. (The factor 1.41 is the square root of 2.) Rms is used because an alternating current usually has the same effect as a direct current when its rms values is the same as the direct current.
Root mean square see rms
ROW see Right of Way
Search coil The commonest way of measuring magnetic fields at power frequencies. A coil of wire has a voltage induced in it by an alternating magnetic field.
Single phase electricity The electrical engineering term for a normal simple circuit, with one live wire and one return wire or neutral. Used to distinguish it from three phase circuits.
SMR Standardised Mortality Ratio. A way of expressing the result of an epidemiological study. The ratio of the mortality in the population examined to that in the whole population, after taking account (“standardising”) of any differences in ages
Statistical significance How likely a given result (in, eg, an epidemiological study) was to have come about just by random chance. Conventionally, if the likelihood of it coming about by chance, in the absence of any actual causal risk is 5% or less, the result is said to be statistically significant
Substation One or more transformers plus their associated switchgear etc.