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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 197 · 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.

NameDateTime takenScore ___ / 40
  1. 1.📏 Voltmeter or ammeter: which one is joined across a part? (a) ammeter (b) voltmeter
  2. 2.💡 Does it save or waste electricity to unplug idle chargers? (a) wastes electricity (b) saves electricity
  3. 3.🔺 A current of 1 A flows when 8 V is joined across a resistor. What is its resistance (in ohms)?
  4. 4.🧮 Five equal 500 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  5. 5.🔍 Which is the odd one out? (a) use daylight to read (b) leave the TV on standby (c) use LED lamps (d) close the fridge quickly
  6. 6.🧮 A 3 V battery is joined to 8 Ω and 4 Ω resistors in series. What current flows (in amperes)? =
  7. 7.🔺 A current of 0.1 A flows through a 15 Ω resistor. What is the voltage across it (in volts)? =
  8. 8.💡 What happens if an LED is put in backwards? (a) it lights brighter (b) it makes a sound (c) it changes colour (d) it does not light
  9. 9.🔺 A current of 50 mA flows when 10 V is joined across a resistor. What is its resistance (in ohms)?
  10. 10.📏 How many ohms make 1 kilo-ohm (kΩ)? (a) 1024 (b) 100 (c) 1000 (d) 10
  11. 11.🧾 A 50 W appliance runs for 2 hours. How many units (kWh) of electricity does it use? =
  12. 12.🔺 A current of 50 mA flows through a 250 Ω resistor. What is the voltage across it (in volts)? =
  13. 13.True or false: on an LED, the round-side leg is the cathode (−). (a) True (b) False
  14. 14.🧩 Which component boosts a small signal? (a) capacitor (b) LED (c) fuse (d) transistor
  15. 15.🔺 In the V-I-R triangle, how do we find I? (a) I = R ÷ V (b) I = V × R (c) I = V ÷ R (d) I = V + R
  16. 16.🔺 A current of 40 mA flows when 10 V is joined across a resistor. What is its resistance (in ohms)?
  17. 17.🔺 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
  18. 18.🔺 A 3.3 V supply is joined across a 330 Ω resistor. What current flows (in milliamperes, mA)?
  19. 19.🌈 A resistor has the colour bands grey, red, black. What is its value (in ohms)?
  20. 20.⚡ A device works on 5 V and takes 2 A. What is its power (in watts)? =
  21. 21.⚡ A device works on 5 V and takes 1 A. What is its power (in watts)? =
  22. 22.⚡ Which formula gives electric power? (a) P = V + I (b) P = V ÷ I (c) P = V × I (d) P = I ÷ V
  23. 23.True or false: on an LED, the longer leg is the anode (+). (a) False (b) True
  24. 24.True or false: the ammeter is joined in series. (a) True (b) False
  25. 25.💡 An LED is joined to a 6 V battery with no resistor; the leg next to the flat edge of its rim goes to the − side. What happens? (a) lights up (b) may burn out (c) does not light
  26. 26.🔺 A current of 10 mA flows through a 150 Ω resistor. What is the voltage across it (in volts)? =
  27. 27.🔺 In the V-I-R triangle, how do we find R? (a) R = I ÷ V (b) R = V + I (c) R = V ÷ I (d) R = V × I
  28. 28.Which of these saves electricity? (a) leave the TV on standby (b) leave fridge door open (c) use old filament bulbs (d) switch off empty rooms
  29. 29.True or false: the voltmeter measures current. (a) True (b) False
  30. 30.True or false: a diode makes a beeping sound. (a) False (b) True
  31. 31.💡 On an LED, is the shorter leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
  32. 32.🌈 A resistor has the colour bands orange, green, orange. What is its value (in ohms)?
  33. 33.🧮 Adding another resistor in series makes the total resistance … (a) bigger (b) smaller (c) stay the same (d) zero
  34. 34.🔺 A current of 50 mA flows when 23.5 V is joined across a resistor. What is its resistance (in ohms)?
  35. 35.🧾 A 1000 W appliance runs for 4 hours. How many units (kWh) of electricity does it use? =
  36. 36.🧮 Two equal 20 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  37. 37.🧮 Four equal 40 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  38. 38.🧩 Which component makes a beeping sound? (a) thermistor (b) motor (c) diode (d) buzzer
  39. 39.True or false: a fuse lets current go one way. (a) False (b) True
  40. 40.🔺 A current of 0.1 A flows through a 3 Ω resistor. What is the voltage across it (in volts)? =

Answer key

  1. voltmeter
  2. saves electricity
  3. 8
  4. 100
  5. leave the TV on standby
  6. 0.25
  7. 1.5
  8. it does not light
  9. 200
  10. 1000
  11. 0.1
  12. 12.5
  13. False
  14. transistor
  15. I = V ÷ R
  16. 250
  17. V = I × R
  18. 10
  19. 82
  20. 10
  21. 5
  22. P = V × I
  23. True
  24. True
  25. may burn out
  26. 1.5
  27. R = V ÷ I
  28. switch off empty rooms
  29. False
  30. False
  31. cathode (−)
  32. 35000
  33. bigger
  34. 470
  35. 4
  36. 10
  37. 10
  38. buzzer
  39. False
  40. 0.3

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