Introduction to Electric Circuits

6 Units and dimensions 1.4 MULTIPLES AND SUBMULTIPLES OF UNITS There is an enormous range of magnitudes in the quantities encoun ...

1.4 Multiples and submultiples of units 7 2 To find the number of centimetres in 1 metre we divide by the submultiple 10 -2. Thu ...

8 Units and dimensions 1.5 SELF-ASSESSMENTTEST 1 Which of the following are units: torque; second; newton; time; kilogram? 2 Whi ...

1.6 Problems 9 7 The permittivity (E) of the medium of an electric field is the ratio of electric flux density (D) to electric f ...

2 Electric circuit elements 2.1 ELECTRICITY The atoms which make up all things consist of a number of particles including the el ...

2.3 Circuit elements 11 to 400 kV, and utilization at around 240 V to 415 V, transformation of voltage levels is required and is ...

12 Electric circuit elements Solution The work done is force times distance moved = F x d - 10 x 5 = 50 J. Voltage source An ide ...

2.3 Circuit elements 13 Ao (~ oB I Figure 2.2 direct current. The symbol for current is I and its unit is called the ampere (A) ...

14 Electric circuit elements v = nI (2.3) where R is the constant of proportionality and is called the resistance of the conduct ...

2.3 Circuit elements 15 Resistivity The resistance of a conductor is directly proportional to its length (1) and inversely propo ...

16 Electric circuit elements Table 2.1 Material Conductivity (S m -1) Resistivity (11 m) Silver 6.1 x 107 1.64 x 10 -8 Copper 5. ...

2.3 Circuit elements 17 resistors in series is therefore the sum of the three individual resistances. In general, for n resistor ...

18 Electric circuit elements V1/V = IR1/[I(R 1 + R2) ] and V, = R1V/(R, + R2) (2.7) Similarly, V2 = R2V/(Ra + R2) (2.8) This sho ...

2.3 Circuit elements 19 R2 t i3 Figure 2.10 I = (V/R~) + (V/R2) + (V/R3) = V[(1/R1) + (1/R2 + (l/R3)] (2.9) If a single resistor ...

20 Electric circuit elements I = VGeq = 100 x 0.34 = 34 A Often we meet just two resistors connected in parallel and it is usefu ...

2.3 Circuit elements 21 Figure 2.13 20A O V 1 I2 R1 = lOf~ R2 = 40t2 Example 2.10 The circuit of Fig. 2.14 is a series-parallel ...

22 Electric circuit elements Internal resistance It was stated earlier in the chapter that an ideal voltage source is independen ...

respectively, its resistance will be R2 = Ro[1 + aoT2] from which we see that RI/R2 = [1 + a0T1]/[l + a0T2] Example 2.12 2.3 Cir ...

24 Electric circuit elements Fig. 2.16. If they are connected in series, determine the maximum possible resistance of the combin ...

2.3 Circuit elements 25 where C is the constant of proportionality and is called the capacitance of the conductor arrangement. I ...