Most accurate definition of kilogram on anvil
Washington: Researchers have developed a novel system to allow a direct comparison of an object being weighed in a vacuum to one outside a vacuum.
The official kilogram, called the International Prototype Kilogram (IPK), is stored in a bureau just outside of Paris, France, and has served as the standard to which all the nations` prototypical kilograms have been compared for the last 125 years.
Every few decades, the national prototypes are carried, usually by hand, to France, where they are measured against the IPK.
But discrepancies between the national prototypes and the official specimen have been increasing at a rate of 0.050 milligrams (mg) every 100 years. And no one knows why.
Patrick Abbott of the National Institute of Standards and Technology (NIST) in Gaithersburg, Md, said that it`s not really clear if the IPK is getting lighter or the national prototypes are getting heavier.
Loss of mass due to wear is unlikely because the IPK is hardly ever taken out of its vault.
The metrologists eventually chose Planck`s constant, which describes the relationship between the energy of a photon and the frequency of light it emits.
Its value has been measured with a relative uncertainty of between 30x10-9 and 35x10-9. However, to assure agreement between the current IPK system and the Planck-defined kilogram, researchers will need to improve their measurements to a relative uncertainty of 20x10-9. And to get better measurements, they will need the ability to perform state-of-the-art metrology in a vacuum.
Currently, researchers use two types of experiment to measure Planck`s constant, and both require vacuums. One method involves determining the number of atoms in a high-purity silicon sphere with a nominal mass of 1 kilogram. The other, called the watt balance, measures the constant by an indirect or "virtual" comparison of mechanical power to electromagnetic power. Using a vacuum ensures that there is no contamination from particles in the air and reduces uncertainty in some of the measurements that are conducted with laser interferometry.
More from India
More from World
More from Sports
More from Entertaiment
- IAF Mirage fighter plane lands on Yamuna Expressway!
- 'Maggi' under regulatory scanner for excess amount of lead, MSG
- Watch: Michelle Obama's 'Gimme Five' fitness video
- When Subramanian Swamy shocked people at a wedding!
- Mumbaikars join hands to save Pakistani teen with rare illness
- Mumbai: Diamond export company denies job to Muslim youth
- Aapke Sitare: Astro prediction for May 21, 2015
- PM Modi speaks at Golden Jubilee celebrations of poet Dinkar’s works
- Mirage 2000 fighter jet landing was part of capability demonstration: IAF
- DNA: IAF Mirage 2000 fighter plane lands successfully on Yamuna expressway
- DNA: Osama documents show 'Indian brother in Madinah' financed al Qaeda
- Coal scam: Naveen Jindal, Madhu Koda and others get bail
- Vadodara: Policemen seen dancing with bar girls
- ISIS executes Syrian fighter using anti-tank rocket launcher
- One year of Modi govt: Arun Jaitley addresses press conference
- CBSE Class 10 Results 2015 to be announced today?
- IAF jet lands on Yamuna expressway
- Check Jharkhand Board jac.nic.in: Class 12th Art Results 2015 declared
- Fawad Khan doesn’t want intimate scenes with Sonam Kapoor?
- Log on to apeamcet.org AP EAMCET Results 2015: Andhra Pradesh EAMCET Marks and AP EAMCET Ranks 2015 declared
- We hire only non-Muslim candidates, diamond export firm tells Muslim youth
- Is MSG in 'Maggi' noodles harmful for you?
- Mumbai firm booked for denying Muslim MBA graduate job on religious grounds, probe ordered
- New IPL rules could see Chennai Super Kings lose MS Dhoni
- Jayalalithaa makes public appearance, meets Governor: As it happened
- `Piku` hits jackpot, does Rs 100 crore business worldwide
- Anurag Kashyap to bid goodbye to India, settle in 'cinema-friendly' France!
- SSLC (tnresults.nic.in) Tenth 10th Results 2015: Tamil Nadu Board Class 10th X Higher Secondary exam results 2015 to be announced shortly
- Geelani's passport application incomplete, cannot be processed: MEA
- IPL 2015, Qualifier 2, Chennai Super Kings vs Royal Challengers Bangalore: Preview