1. Instrumentation (AMME2700) 1 Instrumentation Dr. Xiaofeng Wu

2. Instrumentation (AMME2700) Atom and Electric Charge The charge of an electron Coulombs (C)

3. Instrumentation (AMME2700) Current and Voltage  Current is the time rate of flow of electric charge past a given point  The voltage is the work (energy) required to move a unit positive charge from – terminal to the + terminal.

4. Instrumentation (AMME2700) Basic Electrical Components a)Resistance b)Capacitance c)Inductance

5. Instrumentation (AMME2700) Ohm’s Law

6. Instrumentation (AMME2700) Power and Energy in Circuits

7. Instrumentation (AMME2700) Example 1 A resistor capable of handling safely 5W is to be placed across the terminals of a 10V voltage source. What range of resistances will not exceed the 5W limit?

8. Instrumentation (AMME2700) Kirchhoff’s Current Law  Conservation of Charge  Kirchhoff’s current law (KCL): At any instant the sum of the currents at a junction is zero.

9. Instrumentation (AMME2700) Kirchhoff’s Voltage Law  Kirchhoff’s voltage law (KVL): At any instant in a closed loop, the sum of the voltages acting round the loop is zero.

10. Instrumentation (AMME2700) Example 2 Consider the circuit as shown a)Suppose that the resistance R 1 =8 Ω and R 2 =4 Ω. Find the current I and the voltage v. b)Suppose that i=2.25A and v=42V. Determine the resistance R 1 and R 2.