The candela is the SI base unit relating to luminous intensity. For more information: www.npl.co.uk/r...) Produced in association with the Open University.
Divyalal R.K Sorry to be late. The candela was originally defined so that it could be roughly the luminous intensity of a wax candle. The factor is introduced so that the current definitiom matches the previous one
Wurtt Mapper That’s the problem with S.I. The new definitions try to be more objective but they’re still arbitrarily modified to fit the old definitions.
@@Voivode.of.Hirsir I know. For comparison, a Pascal is a very tiny unit for most everyday measurements but we use kilo pascals a lot. Amperes are rather large but we use miliamps a lot, also. They could have said 1 watt per steradian and we would use milicandelas. But they made it weird by introducing that 1/683 number.
I'm having trouble understanding the "Nit", which is defined as Candelas per square metre. If it were defined as the amount of power contained in a single steridian, from a light emitting with a 1 candela intensity, divided by area, THEN that would make sense, because then, the Nit would be defined in units of power per unit area. However, the Candela is NOT a measure of power - it is a measure of power DENSITY, so to me, it seems non-sensical to say "power per unit area, per unit area". Help!
Useful.. but can you precisely tell why the factor 1/683. . What is special about the number 683?
Divyalal R.K Sorry to be late. The candela was originally defined so that it could be roughly the luminous intensity of a wax candle. The factor is introduced so that the current definitiom matches the previous one
Wurtt Mapper
That’s the problem with S.I. The new definitions try to be more objective but they’re still arbitrarily modified to fit the old definitions.
@@Voivode.of.Hirsir I know. For comparison, a Pascal is a very tiny unit for most everyday measurements but we use kilo pascals a lot. Amperes are rather large but we use miliamps a lot, also. They could have said 1 watt per steradian and we would use milicandelas. But they made it weird by introducing that 1/683 number.
@jmchez candela is a remnant of the imperial system.
VERY GOOD INFORMATION
I'm having trouble understanding the "Nit", which is defined as Candelas per square metre. If it were defined as the amount of power contained in a single steridian, from a light emitting with a 1 candela intensity, divided by area, THEN that would make sense, because then, the Nit would be defined in units of power per unit area. However, the Candela is NOT a measure of power - it is a measure of power DENSITY, so to me, it seems non-sensical to say "power per unit area, per unit area". Help!
thank you :)
11 years
Thank you
thank you!
Helpful.
good
1st