I've been reading a book called Physics Demystified. I'am currently on part 1 Classical physics, chapter 6 units and constants. I have some questions about some defftions and units: The meter: It says that the meter is defined by the distance of light travels through a perfect vacum in 3.33564095 billonths of a second. Why did they chose to base the meter off the amount of time light takes travel between a certin? The candela: not too much of importent question but how exactally do you pronuce it? The Radian: What exactally does plan angular measure mean? Can you please show mean an example like a picture or somthing? The Steradian:What does soild angular measure mean The Joule:I think I understand the joule well but it says. "If reduced to base units in SI, the joule can be expressed in terms of unit mass multiplied by unit distance squared per unit time sqaured: [tex] 1 J kg \cdot m^2/S^2[/tex] I don't think I understand that equation very well. The Watt: this probally going to sound like a stupid question but I'am not sure if I ever properly understand what this means:power The Coulamb: What exactally does electric charge quantity mean The Ohm: I don't need to know what anything means about it but It says that the ohm is the standerd unit of electrical resientance. I thought the Ohm can be used on things other then electricity too? The Farad: what exactally does capacitance mean? The Henery: What exactally does inducatnce mean? The Weber: What exactally does magnetic flux mean? The Tesla:What exactaly does magnetic flux density mean I probally will have more questions later. I do understand what they mean but I just want to make sure I understand what they mean properly.