1. Electrical Components and Circuits
Chapter 2:
Electrical Components and Circuits

3. Bread board
Printed circuit board

4. Laws of Electricity
1, Ohm’s Law V = iR V: potential difference in volts between two points in a circuit (work/coulomb = joule/coulomb) i: current, R: resistance 2. Kirchhoff’s law (1) current law: the algebraic sum of currents around any points in a circuit is zero. (2) voltage law: the algebraic sum of voltages around a closed loop is zero. 3. Power law P = i ·V = i ·(iR) = i2R

5. Direct-Current Circuits
Series Circuit

6. Direct-Current Circuits
Series Circuit
Rs: total resistance of a series circuit

7. Direct-Current Circuits
Voltage Divider
provide voltage that are variable functions of an input voltage
Potentiometer:

8. Digital Voltmeter and Multimeter
Can be used to measure DC potentials, currents, and resistance
Voltage Measurement
Current Measurement
Loading error in current measurement: Table 2-2.
Er = -Rstd/(RL+Rstd) x 100% (2-20); small Rstd/RL  low error

9. Digital Voltmeter and Multimeter
Resistance Measurement

10. Loading Errors in Voltage Measurement

11. Glass/Calomel Electrode (pH electrode)
Instrument for measuring cell potentials
Glass/Calomel Electrode (pH electrode)
True potential = V
Internal resistance = 20 MΩ
Measuring device = 100 MΩ
Relative error = ?
If RM= 1000 MΩ
EM = V
If RM= 1x104 MΩ
EM = V

12. Oscilloscope - a most useful and versatile laboratory instrument
- a graph (e.g. electrical signal)-displaying device
- show how signals change over time
This simple graph can tell you many things about a signal:
-determine time and voltage
-calculate the frequency of an oscillating signal

13. Oscilloscope

14. Oscilloscope
What can you do with it?
Oscilloscopes are used by everyone from television repair technicians to scientists.
Scientific data can be gathered by an oscilloscope

15. Oscilloscope
Oscilloscope block diagram

16. Semiconductor Diodes
Breakdown voltage