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Tham khảo tài liệu 'microengineering mems and interfacing - danny banks part 14', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Amplifiers and Filtering 243 Notice that an instantaneous change in current requires an infinite voltage drop across the inductor. If an attempt is made to switch an inductive load a circuit that is being electrically powered and contains an inductive element off the current has to go somewhere. In the absence of any provision made for this it will break down the insulation of the switch causing a spark arc . Also note that the inductor is a short circuit to DC and an open circuit at high frequencies. More Units Resistance is measured in ohms Capacitance is measured in farads F Inductance is measured in henries H 11.1.1.6 The Ideal Voltage Source The ideal constant-voltage source Figure 11.1g will maintain a constant voltage drop across its terminals no matter what. This means current may flow into or out of either terminal and it can even supply the practically impossible infinite current necessary to charge a capacitor instantaneously. This makes it somewhat similar to an ideal wire with a constant voltage drop placed across it. 11.1.1.7 The Ideal Current Source The ideal constant-current source Figure 11.1h and Figure 11.1i will maintain a constant current flow in the direction indicated by the arrow no matter what voltage drop appears across it. This makes it somewhat similar to an ideal open circuit with a constant current flowing through it. The previous descriptions may be a little counterintuitive current flowing through an open circuit but they are useful. Deeper consideration of the concepts introduced in this section will reveal other useful qualities or analogies some of which will become apparent later see the book by Bogart for a complete introduction to the subject 1 . Note on Strange-Seeming Analogies In the case of the ideal current source it can be found in Subsection 11.1.1.2 that no current will flow through an open circuit irrespective of the voltage dropped across it. Turning the analogy around one could argue that the open circuit is a .
