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First of all, in an active circuit, there are voltages flowing through various nodes. If you try to measure the resistor, those voltages will cause error in your meter, or may damage your meter. Second of all, even if you cut the power, any loop in the circuit around the resistor will affect the measured impedance. Unless you are certain that only the resistor will see the current introduced by the meter, you must take the resistor out of circuit to measure it.
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Why would never measure resistance in a circuit carrying a current?
If the circuit is carrying current then that means that the load (resistance) is in the circuit. if an ohm meter is connected in the live circuit then there would be some voltage drop at the ohm meter but as the meter has very less resistance, this would damage the instrument.
Where do you set the dial when you are measuring resistance on house current?
YOU DO NOT "measure resistance on house current".You never measure resistance of anything that has any path to any source ofpower ... not to a wall outlet, a battery, a windmill, a solar panel, etc. You onlymeasure resistance when all power is REMOVED from the circuit or componentyou're measuring. Then, the range you choose for the ohmmeter depends onthe component or circuit you're measuring, NOT on how it's powered when it'sturned on.
What is difference between ideal current source and practical current source?
Internal resistance. The ideal current source has no internal resistance in parallel with it (if it was set to supply no current it would act as an open circuit), and all the current it supplied would have to flow through its load (even if the load was an open circuit, in which case the voltage across the current source would be infinite). A real current source has the practical limitation that it must have an internal resistance in parallel with it, therefor some of the current it supplied is bypassed through that internal resistance and never reaches the load (if the load was an open circuit, then all the current supplied is bypassed and the resulting voltage drop across the internal resistance limits the voltage across the current source).
What meter must NEVER be connected to a circuit when the circuit power is turned on?
An Ohmmeter.
What is the impedence?
Impedance is the complex form of resistance. Impedance takes into account capacitance and inductance in a circuit as well. Impedance can be represented as resistance as a function of frequency.See link.AnswerImpedance is not a 'complex form of resistance'. It is the vector sum of a circuit's resistance and reactance. In electrical engineering, 'resistance' has a very specific meaning, and cannot be used to denote 'opposition'.
