Kiloelectronvolts to British Thermal Units (keV to BTU)
1 kiloelectronvolt equals 1.518570443×10⁻¹⁹ British thermal units (rounded).
How to convert kiloelectronvolts to British thermal units
To convert kiloelectronvolts to British thermal units, multiply the number of kiloelectronvolts by 1.518570443×10⁻¹⁹. The factor is rounded to 10 significant digits. To go the other way, multiply British thermal units by 6.585140678×10¹⁸ (rounded).
British thermal units = kiloelectronvolts × 1.518570443×10⁻¹⁹
Example: 10 kiloelectronvolts = 1.518570443×10⁻¹⁸ British thermal units.
The 'calorie' on food labels is really a kilocalorie. The thermochemical calorie (4.184 J) is used here unless marked IT.
About these units
Kiloelectronvolt (keV)
1,000 electronvolts. X-ray photon energies are in this range.
X-rays are the usual home of the keV. Wilhelm Roentgen discovered them on 8 November 1895, and their photon energies span about 100 eV to 100 keV. Photons above roughly 5 to 10 keV count as hard X-rays, while lower ones are soft. Medical diagnostic tubes run at 20 to 150 kilovolts, which sets the highest photon energies of a radiograph at about 20 to 150 keV. One keV is 1.602176634 x 10^-16 J.
Fusion research uses it for temperature. A magnetic confinement plasma at about 15 keV corresponds to roughly 174 million kelvin. Compared with the electronvolt, a kiloelectronvolt is a thousand times larger, so it lies well above the 1 to 10 eV of chemical bonds, yet far below the millions of electronvolts released in nuclear reactions.
1 kiloelectronvolt = 1.602176634×10⁻¹⁶ joules (exactly).
Sources: Wikipedia: X-ray; Wikipedia: Electronvolt
British Thermal Unit (BTU)
The International Table BTU, exactly 1,055.05585262 joules. The energy to heat one pound of water by one degree Fahrenheit; used for heating, cooling and gas appliances in the US.
Few energy units come in as many versions as the British thermal unit. It was defined as the heat needed to raise one pound of liquid water by one degree Fahrenheit, but because water's heat capacity shifts slightly with temperature, definitions differ by up to 0.5 percent: about 1,054.35 J for the thermochemical Btu, 1,054.80 J at 59 degrees Fahrenheit (used for American natural gas pricing), 1,054.68 J at 60 degrees (mainly Canadian), and 1,059.67 J at 39 degrees. A 1942 note suggests the term apparently arose in the United States and was later adopted in Britain.
The version on this site is the International Table Btu, about 1,055.06 J, which comes from the international steam table conferences that tied heat units to the joule. Joule's own 1850 experiments gave 772.692 foot-pounds of work per Btu, the number that first linked heat to mechanical effort.
Today the Btu survives in natural gas pricing (MMBtu means a million Btu), US building energy reporting, and equipment ratings in Btu per hour. One ton of air-conditioning is 12,000 Btu/h, or 3.52 kW. A single wooden kitchen match burning releases about one Btu.
1 British thermal unit = 1,055.055853 joules (approximately).
Sources: Wikipedia: British thermal unit; Wikipedia: James Prescott Joule
Related conversions
- British thermal units to kiloelectronvolts (reverse)
- Kiloelectronvolts to joules
- Kiloelectronvolts to kilojoules
- Kiloelectronvolts to watt-hours
- Kiloelectronvolts to kilowatt-hours
- Kiloelectronvolts to calories
- Kiloelectronvolts to kilocalories
- Joules to British thermal units
- Kilojoules to British thermal units
- Watt-hours to British thermal units
- Kilowatt-hours to British thermal units
- Calories to British thermal units
- Kilocalories to British thermal units
- Megajoules to British thermal units
- Gigajoules to British thermal units
- Megawatt-hours to British thermal units
- Foot-pounds to British thermal units
- Millijoules to British thermal units
- Electronvolts to British thermal units
See all energy units.