# How much time is 1 second!

1. Jan 20, 2010

### samieee

hello
recently this question arose in my mind that how much time is called 1 second?.As 1 meter has an international standard of length which is a platinum-iridium standard bar measured at boiling point and situated in France.1 kg also standardly defined:
.But how 1 second is idealized? what is the amount of 1 second? when clocks oscillate how they measure 1 second?

2. Jan 20, 2010

### ZapperZ

Staff Emeritus
http://hyperphysics.phy-astr.gsu.edu/hbase/acloc.html

Zz.

3. Jan 20, 2010

### f95toli

They you look up the wiki for the definition of the second?

If so you should have seen this

The second is the duration of 9,192,631,770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium 133 atom

meaning that an atomic clock works by counting the frequency of a transition between two atomic energy levels.

4. Jan 20, 2010

### Staff: Mentor

Actually, this is not how a meter is defined. Since 1983 the definition of the meter is:

The metre is the length of the path travelled by light in vacuum during a time interval of 1/299 792 458 of a second.

http://www.bipm.org/en/si/base_units/

5. Jan 21, 2010

### energiste

To answer samieee's original concern, a normal watch (digital or standard) counts the oscillations of a quartz crystal (Which is normally 32,768 Hz). And atomic clocks as zapper pointed out count by measuring the radiation of caesium 133 atom.

6. Jan 21, 2010

### dacruick

yes and to cover your next question. the milliliter is the amount of water enclosed by a 1 centimeter cubed box.

7. Jan 22, 2010

### Ranger Mike

how much time is one second....about 6 months ifin you are talking about First Place checker flag and Second P.....all that late night work, busted knuckles and blood sweat and tears..but ifin you are in P1 and holding off the herd..and win it...priceless..I been on the pit wall watching a 10 second lead drop to one second because we started out on rain tires only to have the sun pop out and the last place car cut thru the pack on slicks..and darn near win it...one second is a life time...