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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 540 · 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 home appliance on the 230 V mains takes 10 A. What is its power (in watts)?
  2. 2.🔺 A current of 0.5 A flows when 2 V is joined across a resistor. What is its resistance (in ohms)?
  3. 3.What does a buzzer do? (a) limits the current (b) turns a fan or wheels (c) beeps for an alarm (d) is a resistance knob
  4. 4.📏 Which unit measures current? (a) ohm (Ω) (b) volt (V) (c) watt (W) (d) ampere (A)
  5. 5.True or false: the voltmeter is joined across a part. (a) False (b) True
  6. 6.🌈 In the resistor colour code, which number does brown stand for?
  7. 7.🔺 A current of 0.25 A flows through a 12 Ω resistor. What is the voltage across it (in volts)? =
  8. 8.💡 On an LED, is the round-side leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
  9. 9.🧮 Four equal 400 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  10. 10.True or false: on an LED, the leg by the flat edge is the anode (+). (a) False (b) True
  11. 11.🧾 One “unit” on an electricity bill is … (a) 1 volt (b) 1 ampere (c) 1 watt (d) 1 kilowatt-hour (kWh)
  12. 12.Which of these is measured in watts (W)? (a) voltage (b) power (c) current (d) how much a part resists
  13. 13.True or false: to close the fridge quickly saves electricity. (a) True (b) False
  14. 14.📏 Voltmeter or ammeter: which one is joined in series? (a) voltmeter (b) ammeter
  15. 15.🔺 A current of 0.1 A flows through a 20 Ω resistor. What is the voltage across it (in volts)? =
  16. 16.💡 An LED is joined to a 9 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) does not light (c) may burn out
  17. 17.🧮 A 1.25 V battery is joined to 2 Ω and 3 Ω resistors in series. What current flows (in amperes)? =
  18. 18.⚡ A home appliance on the 230 V mains takes 1.5 A. What is its power (in watts)?
  19. 19.🔺 A 6 V supply is joined across a 2 Ω resistor. What current flows (in amperes)? =
  20. 20.True or false: resistance is measured in watts (W). (a) False (b) True
  21. 21.🔺 A 6 V supply is joined across a 4 Ω resistor. What current flows (in amperes)? =
  22. 22.⚡ A 1.5 W device works on 1.5 V. What current does it take (in amperes)? =
  23. 23.🌈 A resistor has the colour bands violet, violet, red. What is its value in kilo-ohms (kΩ)? =
  24. 24.Which of these is measured in volts (V)? (a) the flow of charge (b) the push of a cell (c) power (d) how much a part resists
  25. 25.📏 How many kilo-ohms (kΩ) is 8300 Ω? =
  26. 26.True or false: on an LED, the shorter leg is the anode (+). (a) True (b) False
  27. 27.🧮 A 47 Ω resistor is joined in series with two equal 200 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
  28. 28.🔺 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
  29. 29.🧾 A 1000 W appliance runs for 4 hours. How many units (kWh) of electricity does it use? =
  30. 30.🧮 Two equal 10 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  31. 31.🔺 A current of 20 mA flows through a 200 Ω resistor. What is the voltage across it (in volts)? =
  32. 32.🔺 A 2 V supply is joined across a 10 Ω resistor. What current flows (in amperes)? =
  33. 33.💡 An LED is joined to a 9 V battery through a 1000 Ω resistor; the leg next to the flat edge of its rim goes to the − side. What happens? (a) may burn out (b) lights up (c) does not light
  34. 34.What does a resistor do? (a) makes things spin (b) glows using little power (c) limits the current (d) blows if current is high
  35. 35.🧩 Which component is a resistance knob? (a) resistor (b) capacitor (c) potentiometer (d) thermistor
  36. 36.💡 What happens if an LED is put in backwards? (a) it changes colour (b) it makes a sound (c) it lights brighter (d) it does not light
  37. 37.💡 On an LED, is the shorter leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
  38. 38.🧾 A 60 W filament bulb is swapped for a 9 W LED lamp that gives about the same light. Both would run for 4 hours. How many watt-hours (Wh) are saved?
  39. 39.🔺 A current of 0.5 A flows when 7.5 V is joined across a resistor. What is its resistance (in ohms)?
  40. 40.🔺 A current of 0.5 A flows through an 8 Ω resistor. What is the voltage across it (in volts)? =

Answer key

  1. 2300
  2. 4
  3. beeps for an alarm
  4. ampere (A)
  5. True
  6. 1
  7. 3
  8. anode (+)
  9. 100
  10. False
  11. 1 kilowatt-hour (kWh)
  12. power
  13. True
  14. ammeter
  15. 2
  16. may burn out
  17. 0.25
  18. 345
  19. 3
  20. False
  21. 1.5
  22. 1
  23. 7.7
  24. the push of a cell
  25. 8.3
  26. False
  27. 147
  28. R = V ÷ I
  29. 4
  30. 5
  31. 4
  32. 0.2
  33. lights up
  34. limits the current
  35. potentiometer
  36. it does not light
  37. cathode (−)
  38. 204
  39. 15
  40. 4

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