Elec theory

• Electrical Circuit Theory and Technology is a fully comprehensive text for courses in electrical principles, circuit theory and electrical technology, providing 800 worked examples and over 1,350 further problems for students to work through at their own pace
• This book is ideal for students studying engineering for the first time as part of BTEC National and other pre-degree vocational courses, as well as Higher Nationals, Foundation Degrees and first-year undergraduate modules
• John Bird


  The author of the book, former Head of Applied Electronics in the Faculty of Technology at Highbury College, Portsmouth, UK. More recently he has combined freelance lecturing and examining, and is the author of over 130 textbooks on engineering and mathematical subjects with worldwide sales of over one million copies. He is currently lecturing at the Defence School of Marine and Air Engineering in the Defence College of Technical Training at HMS Sultan, Gosport, Hampshire, UK
• The book is dedicated to the memory of Elizabeth
• The book is the 6th edition, published in 2017 by Routledge
• The book covers topics such as basic electrical engineering principles, electrical circuit theory, and electrical technology

  
• Calculator


  Used to perform calculations, especially when numbers are larger and mental arithmetic is not feasible
• Evaluating formulae


  • 378.37 - 298.651 + 45.64 - 94.562
  • 17.35 x 34.27 / 41.53 / 3.76 (to 3 decimal places)
  • (4.527 + 3.63) / (452.51 / 34.75) + 0.468 (to 5 significant figures)
  • 52.34 - (912.5 / 41.46) / (24.6 - 13.652) (to 3 decimal places)
  • 52.14 x 0.347 x 11.23 / 19.73 / 3.54 (to 4 significant figures)
  • 6.852 (to 3 decimal places)
  • (0.036)^2 in engineering form
  • 1.33^(1/2)
  • (0.38)^3 (to 4 decimal places)
  • (0.018)^3 in engineering form
  • 1 / 0.00725 (to 1 decimal place)
• In engineering, calculations are essential and a scientific notation calculator with necessary functions is required
• Practice Exercise 1: Use of calculator

  1. Evaluate 378.37 - 298.651 + 45.64 - 94.562

  2. Evaluate 17.35 x 34.27 / 41.53 correct to 3 decimal places

  3. Evaluate (4.527 + 3.63) / (452.51 / 34.75) + 0.468 correct to 5 significant figures

  4. Evaluate 52.34 - (912.5 / 41.46) / (24.6 - 13.652) correct to 3 decimal places

  5. Evaluate 52.14 x 0.347 x 11.23 / 19.73 correct to 4 significant figures

  6. Evaluate 6.852 correct to 3 decimal places

  7. Evaluate (0.036)^2 in engineering form

  8. Evaluate 1.33

  9. Evaluate (0.38)^3 correct to 4 decimal places

  10. Evaluate (0.018)^3 in engineering form

  11. Evaluate 1 / 0.00725 correct to 1 decimal place

  12. Evaluate 1 / 0.065 - 1 / 2.341 correct to 4 significant figures

  13. Evaluate 2.14

  14. Evaluate (0.22)^5 correct to 5 significant figures in engineering form

  15. Evaluate (1.012)^7 correct to 4 decimal places

  16. Evaluate 1.13 + 2.94 - 4.42 correct to 4 significant figures

  17. Evaluate sqrt(34528) correct to 2 decimal places

  18. Evaluate 3sqrt(17) correct to 3 decimal places

  19. Evaluate 6sqrt(2451) - 4sqrt(46) correct to 3 decimal places
• Practice Exercise 2: Evaluation of formulae


  1. Evaluate the area A of a rectangle when l = 12.4cm and b = 5.37cm

  2. Evaluate the circumference C of a circle when r = 8.40mm

  3. Evaluate R when P = 1500, V = 5 and T = 200

  4. Evaluate the final velocity v when the initial velocity u is 12 m/s, acceleration a is 9.81 m/s^2 and time t is 15 seconds

  5. Evaluate the current I when V is 7.2 V and R is 17.7

  6. Evaluate the distance s when time t is 0.032 seconds and acceleration due to gravity g is 9.81 m/s^2

  7. Evaluate the energy E when capacitance C is 5 x 10^-6 farads and voltage V is 240V

  8. Evaluate the area A of a triangle when base length b is 23.42 m and height h is 53.7m

  9. Evaluate R2 when R1 is 220, alpha is 0.00027 and t is 75.6

  10. Evaluate the density when mass is 2.462 kg and volume is 173 cm^3

  11. Evaluate the resistance RT when R1 is 5.5, R2 is 7.42 and R3 is 12.6

  12. Evaluate the potential difference V when E is 5.62, I is 0.70 and R is 4.30

  13. Evaluate the current I when n is 36, E is 2.20, R is 2.80 and r is 0.50

  14. Evaluate the energy E when L is 5.5H and I is 1.2 A

  15. Evaluate the current I when V is 250V, R is 11.0 and X is 16.2
• Fraction


  Numerator is the top line, denominator is the bottom line
• Proper fraction


  Numerator is smaller than denominator
• Using a calculator to add, subtract, multiply and divide fractions


  1. Use the □ and □□ functions to enter fractions

  2. Use the = button to evaluate the result
• Converting fraction to decimal

  1. 1/4 + 2/3 = 11/12

  2. Evaluate 11/12 = 0.9167 (to 4 decimal places)
• Evaluating 5 1/5 - 3 3/4 using a calculator

  1. Press Shift then the □ function and □ □ □ appears

  2. Type in 5 then → on the cursor key

  3. Type in 1 and ↓ on the cursor key

  4. Type in 5 and 5 1/5 appears on the screen

  5. Press → on the cursor key

  6. Type in - and then press Shift then the □ function and 5 1/5 - □ □ □ appears on the screen

  7. Type in 3 then → on the cursor key

  8. Type in 3 and ↓ on the cursor key

  9. Type in 4 and 5 1/5 - 3 3/4 appears on the screen

  10. Press = and the answer 29/20 appears

  11. Press shift and then S ⇔ D function and 1 9/20 appears

  12. Press S ⇔ D function and the fraction changes to a decimal 1.45
• 5 1/5 - 3 3/4 = 29/20 = 1 9/20 = 1.45 as a decimal
• Expressing 0.275 as a percentage

  0.275 = 0.275 × 100% = 27.5%
• Expressing 17.5% as a decimal number


  17.5% = 17.5/100 = 0.175
• Expressing 37.5% as a fraction

  37.5% = 37.5/100 = 375/1000 = 15/40 = 3/8
• Finding 27% of £65

  27% of £65 = 27/100 × 65 = £17.55
• Stress


  63 MPa
• Stress is directly proportional to strain

  When stress is 63 MPa, strain is 0.0003
• Voltage is 90 mV


  Current is 3 A
• Voltage of 1 mV

  Corresponds to a current of 3/90 A
• Voltage is 60 mV


  Current = 60 * 3/90 = 2 A
• Current is 3 A


  Voltage is 90 mV
• Current is 4.2 A


  Voltage = 30 * 4.2 = 126 mV
• b


  Term in bracket
• c


  Term in bracket
• A = a[b(c + d - e) - f(g - h{j - k})] = a[bc + bd - be - fg + fhj - fhk]
• a - 5 = 8, a = 13
• x + 3 = 7, x = 4
• 6x + 1 = 2x + 9, x = 2
• 4(2r - 3) - 2(r - 4) = 3(r - 3) - 1, r = -2
• 4/x = 2/5, x = 10
• 2√d = 8, d = 16
• p = q + r + s, r = p - q - s
• v = fλ, λ = v/f
• v^2 = 2gh, h = v^2/2g