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The current voltage relation of a diode is given by I = (e1000V/T − 1)mA, where the applied voltage V is in volts and the temperature T is in degree kelvin. If a student makes an error in measuring the current of 5 mA at 300 K, what will be the error in the value of current in mA?
- 0.2 mA
- 0.02 mA
- 0.5 mA
- 0.05 mA
Correct answer: 0.2 mA
Solution
I = e^(1000V/T) - 1, so at I = 5 mA we have e^(1000V/T) = 6. dI/dV = (1000/T) e^(1000V/T) = (1000/300)(6) = 20 per volt. With dV = 0.01 V, dI = 20 * 0.01 = 0.2 mA.
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