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QUESTIONS 1

QUESTIONS 1. EXPERIMENT 1: OHM’S LAW RESISTOR V-I RELATION RESISTOR DEFINITION RELATION . OBJECTIVES. CURRENT MEASUREMENT VOLTAGE MEASUREMENT INTERNAL RESISTANCES OF MEASUREMENT INSTRUMENTS ANALOG/DIGITAL MEASUREMENT INSTRUMENTS RESISTORS RESISTANCE COLOR CODES/TOLERANCES R>0

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QUESTIONS 1

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  1. QUESTIONS 1 EXPERIMENT 1: OHM’S LAW RESISTOR V-I RELATION RESISTOR DEFINITION RELATION Ertuğrul Eriş

  2. OBJECTIVES • CURRENT MEASUREMENT • VOLTAGE MEASUREMENT • INTERNAL RESISTANCES OF MEASUREMENT INSTRUMENTS • ANALOG/DIGITAL MEASUREMENT INSTRUMENTS • RESISTORS RESISTANCE COLOR CODES/TOLERANCES • R>0 • SOURCE OF FALSE RESULTS Ertuğrul Eriş

  3. CURRENT MEASUREMENT Measurement of the element (A) current Disconect one of the terminals wire of element (A) conect the ammeter in serial to the element (A). Ammeter polarity references should match with element (A) current flow reference as in passive sign convention. If the measured current sign negative then element (A) Current flows opposite direction of the reference. Ertuğrul Eriş

  4. VOLTAGE MEASUREMENT Measurement of the element (A) voltage conect the voltmeter in parallel to the element (A). Element (A) polarity references should match with Voltmeter polarity Reference. If the measured voltage sign is negative, then the element (A) Voltage polarity is opposite to the chosen one Ertuğrul Eriş

  5. AMMETER INTERNAL RESISTANCE Rin Rin =Ammeterinternal Resistance Ideal:Rin→0 Expected R1(R2)>>Rin RESULT: Real /Measured currents not the same value!! Ertuğrul Eriş

  6. VOLTMETER INTERNAL RESISTANCE Rin Rin= voltmeter internal Resistance Ideal:Rin→∞ Expected Rin >> R2 RESULT: Real /Measured voltages not the same value!! Ertuğrul Eriş

  7. ANALOG/DIGITAL MEASUREMENT INSTRUMENTS • ANALOG • Internal resistance small for ammeter • Internal resistance highfor voltmeter • DIGITAL • Internal resistance much more smaller for ammeter • Internal resistance much more higher for voltmeter Internal resistances changes by ranges!! Ertuğrul Eriş

  8. RESISTORS RESISTANCE COLOR CODES/TOLERANCES Could there be a resistance value 4680Ω? Ertuğrul Eriş

  9. RESISTORS RESISTANCE COLOR CODES/TOLERANCES • Tolerances could be %5;%10 • Manufacturing • R= 47Ω with %5 tolerance means • R= 47Ω±%5 • 47-47*0,05≤ R ≤ 47+47*0,05 • 44.65 ≤ R ≤ 49,35 • Does «tolerances» effect measurement • Calculation error, limit • Uncertainity/certainity Ertuğrul Eriş

  10. R>0 • RESISTOR’S RESISTANCE VALUES ARE ALWAYS POSITIVE REAL NUMBERS • This number related to physical and chemical properties • NOT NEGATIVE • NOT COMPLEX • NOT EXPONENTIAL Ertuğrul Eriş

  11. PROBABLE SOURCES OF FALSE MEASUREMENTS • Internal resistances of measurement instruments • Elements values tolerances • Reading mistakes • How to avoid these falses!! Ertuğrul Eriş

  12. QUESTIONS • If you plot V/I characteristic of a resistor, which parameter of this characteristic gives R value? Why? • Could there be a V/I characteristic of a resistor which doesn’t include (0, 0) point)Why? • Could there be a resistor V/I characteristic which is in second and fourth region of Cartesian coordinates? Why? • Which ideal elements have no V-I characteristics, but only definition relation?Why? • Does ‘a three digit color coding of resistor values’ limit producible resistor value ranges? Why? If you need to increase these range what would be your solution? • Write down at least three reasons which cause difference between R1 (R2) and R = Vmes/Imes values in the below table? • What are resistances' values in practice? Is any resistance value resistor available in the market? What is resistors' tolerance? Ertuğrul Eriş

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