What is Meter: Definition and 309 Discussions

The metre (Commonwealth spelling) or meter (American spelling; see spelling differences) (from the French unit mètre, from the Greek noun μέτρον, "measure", and cognate with Sanskrit mita, meaning "measured") is the base unit of length in the International System of Units (SI). The SI unit symbol is m.
The metre is currently defined as the length of the path travelled by light in a vacuum in 1/299 792 458 of a second.
The metre was originally defined in 1793 as one ten-millionth of the distance from the equator to the North Pole along a great circle, so the Earth's circumference is approximately 40000 km. In 1799, the metre was redefined in terms of a prototype metre bar (the actual bar used was changed in 1889). In 1960, the metre was redefined in terms of a certain number of wavelengths of a certain emission line of krypton-86. The current definition was adopted in 1983 and modified slightly in 2002 to clarify that the metre is a measure of proper length.

View More On Wikipedia.org
Recent contents Top users
  1. T

    Troubleshooting HP 34401a Voltage Meter Load

    Hi every one, I have a HP 34401a meter that is causing some issues with a high impedance sensor input. when I place only the ground wire ( black ) to the input circuit ground, the sensor reading jumps quiet dramatically, this does not happen if i place only the Red wire. I have tried...
  2. K

    The meter, the second, and the speed of light

    So, I will try to explain this as best as possible. I am literally on the first chapter of a classical mechanics book. The chapter is discussing all the basic SI units...the meter, the second, etc. It's these units that I am having such a hard time understanding. They seem so easy but my...
  3. S

    Meter stick and rock balancing ?

    A uniform meter stick supported at the 25-cm mark is in equilibrium when a 1-kg rock is suspended at the 0-cm end. Is the mass of the meter stick greater than, equal to, or less than the mass of the rock? Explain your reasoning. Thanks in advance for any help!
  4. BiGyElLoWhAt

    Sensor developement for laser power meter

    Not really sure if this should go here or in technology, but it's a physics class sooo... we had to build a device to measure the power of a laser with an output of around 10mW or less. I went with a differential gain amplifier using 2 thermistors, one of which is kept at ambient...
  5. Hardik Batra

    Meter Bridge Experiment: Limitations for Measuring Small Resistance

    why the meter bridge experiment not useful for the measurement of small resistance?
  6. R

    Lithium battery capacity meter

    Dear Friends Is there a good battery capacity measurement device you can recommend? I need to measure how much capacity a lithium pack really has. Thanks. regards Ramone
  7. B

    Thermal Energy in 1 cubic meter of air at room temperature

    Homework Statement How much thermal energy was in 1 cubic meter of air at room temperature. Give your answer in Joules. How much kinetic energy does one cubic meter of air have if it were to hit the ground after falling 100 m? Give your answer in Joules. Which has more energy...
  8. P

    1000 kilo Newton meter (K/Nm) torque

    i want to produce 1000 K/nm of torque using motors and gear , output rpm needed is 30 and 1000 k/ nm of torque 1) motor kva? and rpm ? 2) gear ratio and size ? 3) does it also require flywheel ?
  9. J

    What can a PH meter tell you about the quality of fluid

    What can a PH meter tell you about the quality of fluid it is measuring?
  10. P

    Fluid Mechanics and Venturi meter

    Homework Statement A Venturi meter is constructed with an inlet diameterof 100 mm and a throat diameter of 40 mm. The meter must be calibrated prior to leaving the factory. The meter is installed in a 100 mm diameter water main with a...
  11. E

    Solving Potential Voltage Issues with RS 256-225 Flow Meter

    hi I am having trouble trying to find what i potential to the voltage of a rs 256-225 flow meter. Has anyone got an idea to put me on the right track all i need is the push in the right direction. Thanks
  12. K

    How Do You Calculate Input Signal from Analog Meter Readings?

    Homework Statement 1. For the pointer position in the diagram, what is the input signal if the range is set at 0.3v? (i was just wondering if my path to the solution is correct) (arrow pointing at 1.75) picture attached The Attempt at a Solution Range / scales maximum = #...
  13. M

    Looking to sniff out smart meter RF

    Hey everyone I hope I am posting this in the right place.. After all this is my first post here. I am looking to track down what RF (radio frequency) my local smart meters are broadcasting in. I have been doing some research but would like to know if anyone has any experience with...
  14. M

    Digital Watt Meter Connected To Microcontroller

    Hello all, I am currently working on a project for a client in which my objective is to create an educational light bulb display. The purpose of this display is to demonstrate cost effectiveness between 4 different bulbs (incandescent, high-efficiency incandescent, CFC, and LED). Each...
  15. P

    Incorrectly connected system or bad power meter help please?

    Hi, When using 3 power meters to measure a 3 phase resistive load, I found that each of the power meters showed a pf of exactly 1.00. However, on one phase I was getting a reactive power value. How is this possible? Is this likely to be the sign of a faulty meter or similar?
  16. S

    Flow through a venturi meter (TEL)

    Homework Statement I recently completed an experiment which analysed flow through a venturi meter. We were then asked to plot the total energy line, velocity head line and pressure head line across 11 piezometers connected to the pipeline. Homework Equations ## \frac{P_1}{\rho g} + z_1 +...
  17. N

    Calculate the cost of the energy lost to heat per hour per meter

    Homework Statement A small city requires about ##17 \mbox{MW}## of power. Suppose that instead of using high-voltage lines to supply the power, the power is delivered at ##120 V##. Assuming a two-wire line of 0.60cm -diameter copper wire, estimate the cost of the energy lost to heat per hour...
  18. F

    Flow measurement in venturi meter

    First I am trying to find the theoretical flow rate but I am not able to get the answer because since diameter of the pipe is 0.03m throughout, when I sub into the formula: My A1/A2 will be 1, and 1-1 = 0. And I will get maths error whatever is divided by 0. Am I going in the wrong direction...
  19. A

    Can you get the power used from 1 hour meter reading?

    Can I get that kw used for that hour from reading the meter in one hour? Thanks
  20. L

    Controlling activation of a circuit with a moisture meter

    Hi, I'm building a make shift spectrophotometer. It's only concerned with a narrow bandwidth of visible light. I'm using two LEDs, one which is lit, the other which is co-incident with a sample in between absorbing light from the lit LED. I pass the voltage of the receving LED to an LM358...
  21. W

    Why Did the 1983 Conference Reject Defining c=3x10^8 or 1 m/s?

    Question: In redefining the meter in terms of the speed of light, why did not the delegates to the 1983 General Conference on Weights and Measures simplify matters by defining the speed of light to be 3x10^8 m/s exactly? For that matter, why did they not define it to be 1 m/s exactly? Were...
  22. 7

    Special relativity - 2 meter sticks mooving along each other

    Homework Statement Two sticks (both with the proper length ##\scriptsize 1m##) travel one toward another along their lengths. In the proper system of one stick they measure time ##\scriptsize 12.5ns## between two events: right ends are aligned (this happens first) left ends are aligned...
  23. S

    Causes for 1 meter of clay over meters of sand

    In the yards of my neighborhood there is about 1 meter of a light brown clay over meters of sand. I'm curious what causes this geology. This is in the USA in the 88005 area code. I speculate that clay is caused by floods of the Rio Grande river, but I don't know what explains the sand. There...
  24. G

    Using torque to find mass of meter stick

    Homework Statement 22) A 1-kg rock is suspended from the tip of a meter stick at the 0- cm mark so that the meter stick balances like a see-saw when the fulcrum is at the 25-cm mark. From this information, what is the mass of the meter stick? A) 1/4 kg B) 1/2 kg C) 3/4 kg D) 1 kg...
  25. N

    Simple Harmonic Motion on a Uniform Meter Stick

    Homework Statement A uniform meter stick of mass M is pivoted on a hinge at one end and held horizontal by a spring with spring constant k attached at the other end. If the stick oscillates up and down slightly, what is its frequency? Homework Equations τ=rFsinθ f=(1/2π)√(k/m) F=kx...
  26. O

    Explanation on Shunt resistor from meter

    I know meter shunts are used to direct most of the current away from the meter coil but my question is if you direct most of current away from the coil, how is the meter measuring the current flow accurately. Im kinda slow in the head so no complex fried banana explanation. tnx
  27. Greg Bernhardt

    Stargazing $1.3 billion Thirty Meter Telescope (TMT) gets approved

    http://news.sciencemag.org/scienceinsider/2013/03/thirty-meter-telescope-gets-smal.html
  28. S

    (D'arsonval galvanometer) moving coil meter

    Hello, just been reading a little bit about the basics of moving coil meter and one thing is bugging me. First if we have a basic square looped coil in and uniform magnetic field. There is torque ( m x B ) due to the magnetic field and then there is the system/spring attached to the coil...
  29. A

    Kinetic Energy in water and the rate carried across each square meter

    [b]1. Consider an ocean current flowing at 2.5m/s a) How much kinetic energy is contained in a cubic volume of water that measures 1m on each side? The density of seawater is about 1030kg/m3 b) If the flow is perpendicular to one of the cube faces, what is the rate at which the current carries...
  30. P

    Calculating Reaction Time from Dropped Meter Stick

    Homework Statement A meter stick is held vertically above your hand, with the lower end between your thumb and first finger. On seeing the meter stick released, you grab it with these two fingers. You can calculate your reaction time from the distance the meter stick falls, read directly from...
  31. C

    Kill-A-Watt meter alters runtime on UPS?

    I’m hoping someone can help me. I have several UPSs. Among them is a cheap Newpoint UPS. It’s something like 275W/550VA. I think the battery is dead or near-dead, was recently experimenting with it to confirm, and found some very interesting behavior. I have a 120V lamp with a LED bulb in...
  32. K

    Notation of permittivity in farads per meter question

    I am using an old textbook as a reference, and the equation given for the electrical permittivity of free space ε0 is given in terms of: (Fm-1) where this measurement notation represents farads per meter. Why the superscript of -1 in the notation?
  33. alexmahone

    Moments - Balancing a weighted meter stick

    Moments -- Balancing a weighted meter stick A meter stick is found to balance at the 49.2cm mark when placed on a fulcrum. When a 46.0g mass is attached at the 14.7cm mark, the fulcrum must be moved to the 38.7cm mark for balance. What is the mass of the meter stick? I know I have to use...
  34. N

    Find the Speed of a Falling Meter Stick

    A meter stick is held vertically with one end on the floor and is then allowed to fall. Find the speed of the other end just before it hits the floor, assuming that the end on the floor does not slip. (Hint: Consider the stick to be a thin rod and use the conservation of energy principle)...
  35. A

    How to convert decibel micro volt per meter?

    anyone know how to convert decibel micro volt per meter to dbm?this term are using for rf electromagnet...tq..
  36. C

    A moving-coil meter, with internal resistance .

    A moving-coil meter, with internal resistance... Homework Statement A moving-coil meter, with internal resistance Rmeter = 15 Ω produces full-scale deflection for a current of 13 mA. Design a voltmeter, as shown below, which can measure voltages in the range 0 - 14 V. What is the required...
  37. R

    What is typical internal resistance of analog voltage meter?

    What is typical internal resistance of a voltage meter on a handheld analog multimeter, and also what is typical resistance on its ammeter?
  38. S

    Calculating the tesion in a string holding a 1 meter stick

    A meterstick (L = 1 m) has a mass of m = 0.13 kg. Initially it hangs from two short strings: one at the 25 cm mark and one at the 75 cm mark. What is the tension in the left string right after the right string is cut? Calculating the free body diagram where we put the acceleration...
  39. A

    Electric potential at the center of meter stick

    Two 3.00-μC charges are at the ends of a meter stick. Find the electrical potential for the center of the meter stick. V=kq/r I just want to confirm my answer here. What I did is solve this for both charges in the equation above using r = 0.5m q= 3.00 uC. So I factored out k/r...
  40. T

    RS485 to RS232 (Energy meter connection)

    Hello, We've recently decided that our energy monitors need to be reseted; to do so we need to connect to the devices as this can't be done from their menu (https://www.gavazzionline.com/pdf/EM2172DDS.pdf this is the meter). In order to connect we've acquired an RS485>RS232 converter...
  41. R

    Why Does My RLC Meter Show a Negative Capacitance Value?

    Hello everyone,now i still working my final project for a graduation.. and i must measuring my tools using RLC meter, but when i measure,my RLC meter showing a negative symbols (-) for the value of capacitance.. and when i check the manual book,there is'nt an explanation about it.. did...
  42. T

    Why Did Shakespeare Write in Iambic Pentameter?

    I watched some performances of midsummer nights dream on utube sort of expecting to hear this meter, but instead the actors seem to only adhere to the periods and commas in the text. The rest of the vatiation seems to just depend on the actor. I was told that one of the reasons for iambic...
  43. L

    Can GM gamma meter be sensitive for neutron radiation?

    Hi, I'm a new member in the forum. I own two similar GM military grade meters with calibration certificates, calibrated for gamma-rays metering and each one has two tubes filled with helium, argon (or neon), halogen (or quenching) gases. When I am exposed to some radiation source, my GM meter...
  44. N

    How many atoms per meter are there in a carbon nano tube?

    I'm interested in the theoretical minimum number, so like the extruded buckyball ball? I'm trying to work out if there are enough carbon atoms in a 'piece of paper' to reach the moon. :) Which brings me to the next question : how many carbon atoms are there in a piece of paper? Or...
  45. A

    Power loss between the electricity meter and the building

    The hydro meter for my house sits on a pole at the front of my property (5.5 acres) approximetly 200 - 250ft from my house I can't give you the wire size that runs under ground. My question is: Is there a loss of power in the distance from the meter to the house and would this result in my...
  46. C

    Appropriate arrangement of light meter circuit with LDR and resistor question:

    Homework Statement If you have a series 'light-meter' circuit with a cell EMF of 12V that must include both an LDR and a resistor only (in series), which way would you put them around to make this most effective and why? ~~~That is, would you have LDR then resistor, or resistor then LDR...
  47. F

    How Does a Sound Meter Interpret Different Frequency Ranges?

    Hello Forum, I am planning to buy a noise meter. This instrument receives a signal that carries a certain total power. A spectrum analyzer tells us how this total power is distributed among the various frequency components. When the sound meter gives a reading in the dB (A) scale it is...
  48. T

    Calculating Force Exerted by a Pivot on a Meter Rule

    Homework Statement The weight of a uniform meter rule is 1.5N. Calculate the force exerted by the pivot on the meter rule. The answer in the back of the book say it is magnitude of 0.5N downwards, I have tried every combo of equation from m=f*d to W=m*g There are 3 question before...
  49. A

    Reading Error by Two Unsynchronized Power Meter

    Hi everyone, I've been searching and googling for the answer to no avail, so I'm just wondering if anyone at PF could help me out. It's for my work assignment, by the way. I have two power meters connected at two ends of a transmission line (assume it's 33kVAC). At each power meter, there...
  50. J

    Electric company meter reading

    I put up a security gate requiring a code at the entrance to my property 6 months ago but the electric company has never requested access to read my meter. I have an old fashioned non-digital meter that cannot be seen from the road. My bill references a specific KWh usage. How does the power...
Back
Top