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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 260 · 40 questions
TalentJR

Remember (Find the topic, use the formula): Find the topic and the formula: V = I × R, I = V ÷ R, R = V ÷ I, P = V × I, units = W × h ÷ 1000. Change mA to A and kΩ to Ω before using a formula. Check: put your answer back into the formula.

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  1. 1.🔺 A 10 V supply is joined across a 500 Ω resistor. What current flows (in milliamperes, mA)?
  2. 2.🧮 Adding another resistor in series makes the total resistance … (a) zero (b) bigger (c) stay the same (d) smaller
  3. 3.Which of these is measured in watts (W)? (a) voltage (b) how much a part resists (c) power (d) resistance
  4. 4.⚡ Which formula gives electric power? (a) P = I ÷ V (b) P = V ÷ I (c) P = V + I (d) P = V × I
  5. 5.What does a fuse do? (a) boosts a small signal (b) glows using little power (c) blows if current is high (d) senses how bright it is
  6. 6.True or false: on an LED, the longer leg is the cathode (−). (a) False (b) True
  7. 7.💡 On an LED, is the round-side leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
  8. 8.🌈 A resistor has the colour bands white, green, orange. What is its value in kilo-ohms (kΩ)? =
  9. 9.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark an 89000 Ω resistor? (a) white-grey-orange (b) grey-white-yellow (c) grey-white-red (d) grey-white-orange
  10. 10.🔺 In the V-I-R triangle, how do we find V? (a) V = I + R (b) V = I × R (c) V = I ÷ R (d) V = R ÷ I
  11. 11.🔺 A current of 1 A flows through a 4 Ω resistor. What is the voltage across it (in volts)? =
  12. 12.🧮 Four equal 80 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  13. 13.🧮 Two equal 10 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  14. 14.⚡ A home appliance on the 230 V mains takes 0.5 A. What is its power (in watts)?
  15. 15.💡 An LED is joined to a 6 V battery through a 470 Ω resistor; its long leg goes to the − side and its short leg to the + side. What happens? (a) may burn out (b) does not light (c) lights up
  16. 16.🌈 A gold fourth band on a resistor means the value may be off by … (a) 25 % (b) 5 % (c) 50 % (d) 0 %
  17. 17.📏 How many watts (W) is 3 kW?
  18. 18.🧮 Two resistors in parallel give a total that is … (a) their sum (b) more than either one (c) less than either one (d) always zero
  19. 19.🧮 Resistors of 47 Ω and 330 Ω are joined in series. What is the total resistance (in ohms)?
  20. 20.⚡ Power tells us … (a) the size of a cell (b) the length of a wire (c) the colour of light (d) energy used each second
  21. 21.True or false: a thermistor has coloured bands. (a) False (b) True
  22. 22.⚡ A device works on 1.5 V and takes 1 A. What is its power (in watts)? =
  23. 23.🧮 A 14 V battery is joined to 12 Ω and 2 Ω resistors in series. What current flows (in amperes)? =
  24. 24.⚡ A 0.15 W device works on 1.5 V. What current does it take (in amperes)? =
  25. 25.🧾 A 75 W filament bulb is swapped for a 12 W LED lamp that gives about the same light. Both would run for 8 hours. How many watt-hours (Wh) are saved?
  26. 26.🧩 Which part changes electrical energy into sound? (a) a buzzer (b) a diode (c) a resistor (d) a capacitor
  27. 27.🔺 A current of 3 A flows through a 5 Ω resistor. What is the voltage across it (in volts)? =
  28. 28.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark an 800 Ω resistor? (a) white-grey-brown (b) grey-black-red (c) grey-black-brown (d) grey-black-black
  29. 29.🔺 A current of 10 mA flows when 2.5 V is joined across a resistor. What is its resistance (in ohms)?
  30. 30.🧮 Resistors of 330 Ω, 33 Ω and 220 Ω are joined in series. What is the total resistance (in ohms)?
  31. 31.🔺 A current of 10 mA flows through a 250 Ω resistor. What is the voltage across it (in volts)? =
  32. 32.🔺 In the V-I-R triangle, how do we find R? (a) R = V ÷ I (b) R = V + I (c) R = I ÷ V (d) R = V × I
  33. 33.🔺 A 6 V supply is joined across a 6 Ω resistor. What current flows (in amperes)? =
  34. 34.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark an 18 Ω resistor? (a) brown-grey-black (b) red-grey-black (c) brown-grey-brown (d) grey-brown-black
  35. 35.⚡ A 2.4 W device works on 12 V. What current does it take (in amperes)? =
  36. 36.True or false: the voltmeter measures current. (a) False (b) True
  37. 37.True or false: a diode limits the current. (a) False (b) True
  38. 38.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) gets smaller (b) gets bigger (c) becomes zero (d) stays the same
  39. 39.What does a resistor do? (a) boosts a small signal (b) beeps for an alarm (c) limits the current (d) makes a beeping sound
  40. 40.🧾 A 100 W appliance runs for 2 hours. How many units (kWh) of electricity does it use? =

Answer key

  1. 20
  2. bigger
  3. power
  4. P = V × I
  5. blows if current is high
  6. False
  7. anode (+)
  8. 95
  9. grey-white-orange
  10. V = I × R
  11. 4
  12. 20
  13. 5
  14. 115
  15. does not light
  16. 5 %
  17. 3000
  18. less than either one
  19. 377
  20. energy used each second
  21. False
  22. 1.5
  23. 1
  24. 0.1
  25. 504
  26. a buzzer
  27. 15
  28. grey-black-brown
  29. 250
  30. 583
  31. 2.5
  32. R = V ÷ I
  33. 1
  34. brown-grey-black
  35. 0.2
  36. False
  37. False
  38. gets smaller
  39. limits the current
  40. 0.2

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