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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 74 · 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.True or false: the voltmeter is joined in series. (a) True (b) False
  2. 2.💡 What happens if an LED is put in backwards? (a) it makes a sound (b) it changes colour (c) it does not light (d) it lights brighter
  3. 3.📏 How many kilo-ohms (kΩ) is 4500 Ω? =
  4. 4.📏 Which unit measures energy used each second? (a) ohm (Ω) (b) ampere (A) (c) volt (V) (d) watt (W)
  5. 5.🔺 A current of 25 mA flows through a 220 Ω resistor. What is the voltage across it (in volts)? =
  6. 6.🔺 A current of 1 A flows through a 10 Ω resistor. What is the voltage across it (in volts)? =
  7. 7.True or false: current is measured in watts (W). (a) False (b) True
  8. 8.🧮 Resistors of 470 Ω, 470 Ω, 100 Ω and 47 Ω are joined in series. What is the total resistance (in ohms)?
  9. 9.🔺 A current of 10 mA flows through a 220 Ω resistor. What is the voltage across it (in volts)? =
  10. 10.🔺 A current of 2.5 A flows when 20 V is joined across a resistor. What is its resistance (in ohms)?
  11. 11.🔺 In the V-I-R triangle, how do we find R? (a) R = V ÷ I (b) R = I ÷ V (c) R = V × I (d) R = V + I
  12. 12.🧮 Three equal 300 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  13. 13.True or false: a capacitor stores a little charge. (a) False (b) True
  14. 14.🧮 Adding another resistor in series makes the total resistance … (a) zero (b) bigger (c) stay the same (d) smaller
  15. 15.🧾 A 40 W filament bulb is swapped for a 6 W LED lamp that gives about the same light. Both would run for 7 hours. How many watt-hours (Wh) are saved?
  16. 16.🔺 A current of 10 mA flows through a 250 Ω resistor. What is the voltage across it (in volts)? =
  17. 17.📏 Which unit measures resistance? (a) ohm (Ω) (b) volt (V) (c) ampere (A) (d) watt (W)
  18. 18.⚡ A home appliance on the 230 V mains takes 1 A. What is its power (in watts)?
  19. 19.What does a potentiometer do? (a) turns a fan or wheels (b) is a resistance knob (c) blows if current is high (d) has coloured bands
  20. 20.⚡ A home appliance on the 230 V mains takes 0.5 A. What is its power (in watts)?
  21. 21.🌈 A resistor has the colour bands grey, white, yellow. What is its value in kilo-ohms (kΩ)? =
  22. 22.💡 An LED is joined to a 12 V battery with no 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
  23. 23.🔺 A current of 25 mA flows through a 100 Ω resistor. What is the voltage across it (in volts)? =
  24. 24.⚡ A device works on 9 V and takes 1 A. What is its power (in watts)? =
  25. 25.🔺 A current of 1.5 A flows when 6 V is joined across a resistor. What is its resistance (in ohms)?
  26. 26.What does a fuse do? (a) has coloured bands (b) is a resistance knob (c) blows if current is high (d) limits the current
  27. 27.True or false: on an LED, the longer leg is the cathode (−). (a) True (b) False
  28. 28.🧩 A capacitor in a circuit can … (a) make light (b) store charge briefly (c) spin a wheel (d) measure heat
  29. 29.🔺 In the V-I-R triangle, how do we find I? (a) I = V + R (b) I = R ÷ V (c) I = V ÷ R (d) I = V × R
  30. 30.🧮 Four equal 20 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  31. 31.🔺 A current of 20 mA flows when 9.4 V is joined across a resistor. What is its resistance (in ohms)?
  32. 32.📏 Which unit measures voltage? (a) volt (V) (b) ampere (A) (c) ohm (Ω) (d) watt (W)
  33. 33.🔺 A current of 20 mA flows through a 400 Ω resistor. What is the voltage across it (in volts)? =
  34. 34.💡 Does it save or waste electricity to use daylight to read? (a) saves electricity (b) wastes electricity
  35. 35.🧩 Which component beeps for an alarm? (a) LED (b) potentiometer (c) buzzer (d) motor
  36. 36.💡 On an LED, is the leg by the flat edge the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
  37. 37.📏 Which unit measures power? (a) volt (V) (b) ampere (A) (c) ohm (Ω) (d) watt (W)
  38. 38.🔺 A current of 0.1 A flows through a 15 Ω resistor. What is the voltage across it (in volts)? =
  39. 39.🧮 Four equal 100 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  40. 40.🌈 A resistor has the colour bands green, red, orange. What is its value (in ohms)?

Answer key

  1. False
  2. it does not light
  3. 4.5
  4. watt (W)
  5. 5.5
  6. 10
  7. False
  8. 1087
  9. 2.2
  10. 8
  11. R = V ÷ I
  12. 100
  13. True
  14. bigger
  15. 238
  16. 2.5
  17. ohm (Ω)
  18. 230
  19. is a resistance knob
  20. 115
  21. 890
  22. may burn out
  23. 2.5
  24. 9
  25. 4
  26. blows if current is high
  27. False
  28. store charge briefly
  29. I = V ÷ R
  30. 5
  31. 470
  32. volt (V)
  33. 8
  34. saves electricity
  35. buzzer
  36. cathode (−)
  37. watt (W)
  38. 1.5
  39. 25
  40. 52000

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