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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 454 · 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.💡 On an LED, is the longer leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
  2. 2.🔺 A current of 20 mA flows through a 250 Ω resistor. What is the voltage across it (in volts)? =
  3. 3.⚡ A device works on 1.5 V and takes 0.25 A. What is its power (in watts)? =
  4. 4.⚡ A home appliance on the 230 V mains takes 10 A. What is its power (in watts)?
  5. 5.True or false: energy used each second is measured in volts (V). (a) True (b) False
  6. 6.True or false: on an LED, the longer leg is the anode (+). (a) True (b) False
  7. 7.True or false: the ammeter is joined across a part. (a) True (b) False
  8. 8.🧾 One “unit” on an electricity bill is … (a) 1 ampere (b) 1 volt (c) 1 watt (d) 1 kilowatt-hour (kWh)
  9. 9.💡 A red LED uses 2 V and should get 20 mA. It runs from a 5 V supply. What resistor (in ohms) is needed in series?
  10. 10.🧩 Which component makes things spin? (a) motor (b) potentiometer (c) buzzer (d) LED
  11. 11.⚡ A device works on 1.5 V and takes 0.2 A. What is its power (in watts)? =
  12. 12.⚡ A 0.75 W device works on 3 V. What current does it take (in amperes)? =
  13. 13.🌈 A gold fourth band on a resistor means the value may be off by … (a) 0 % (b) 25 % (c) 50 % (d) 5 %
  14. 14.🧮 Two equal 40 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  15. 15.📏 How many kilo-ohms (kΩ) is 2300 Ω? =
  16. 16.🌈 In the resistor colour code, which number does yellow stand for?
  17. 17.🔺 A current of 0.2 A flows through a 2 Ω resistor. What is the voltage across it (in volts)? =
  18. 18.🧾 Which lamp gives the same light for the least power? (a) a filament bulb (b) an LED lamp (c) an oil lamp (d) a candle
  19. 19.True or false: the ammeter measures voltage. (a) False (b) True
  20. 20.📏 In the water-pipe picture of a circuit, current is like … (a) the flow of water (b) the pipe colour (c) a narrow pipe (d) the water pressure
  21. 21.🔺 A current of 2.5 A flows when 25 V is joined across a resistor. What is its resistance (in ohms)?
  22. 22.🧮 Four equal 80 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  23. 23.🧩 Which component smooths a wobbly supply? (a) buzzer (b) capacitor (c) diode (d) transistor
  24. 24.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 140 Ω resistor? (a) yellow-brown-brown (b) brown-yellow-black (c) brown-yellow-brown (d) brown-yellow-red
  25. 25.🧮 A 1.6 V battery is joined to 4 Ω and 12 Ω resistors in series. What current flows (in amperes)? =
  26. 26.🧩 Which part changes electrical energy into movement? (a) an LED (b) a resistor (c) a fuse (d) a motor
  27. 27.Which of these is measured in watts (W)? (a) current (b) energy used each second (c) voltage (d) how much a part resists
  28. 28.🔺 A current of 25 mA flows through a 470 Ω resistor. What is the voltage across it (in volts)? =
  29. 29.💡 Does it save or waste electricity to use old filament bulbs? (a) wastes electricity (b) saves electricity
  30. 30.🔺 In the V-I-R triangle, how do we find R? (a) R = V × I (b) R = V + I (c) R = V ÷ I (d) R = I ÷ V
  31. 31.💡 What does LED stand for? (a) large electric dial (b) low energy device (c) light-emitting diode (d) light energy dial
  32. 32.🔺 A current of 0.1 A flows through a 15 Ω resistor. What is the voltage across it (in volts)? =
  33. 33.🔺 A current of 50 mA flows when 20 V is joined across a resistor. What is its resistance (in ohms)?
  34. 34.📏 How many watts (W) is 3.8 kW?
  35. 35.🔺 A current of 40 mA flows through a 220 Ω resistor. What is the voltage across it (in volts)? =
  36. 36.💡 A red LED (it uses 2 V) is joined with a 150 Ω resistor to a 2.75 V supply. What current flows (in mA)?
  37. 37.⚡ A device works on 9 V and takes 0.5 A. What is its power (in watts)? =
  38. 38.True or false: to use daylight to read saves electricity. (a) True (b) False
  39. 39.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) gets smaller (b) becomes zero (c) stays the same (d) gets bigger
  40. 40.🧮 Two resistors in parallel give a total that is … (a) less than either one (b) always zero (c) more than either one (d) their sum

Answer key

  1. anode (+)
  2. 5
  3. 0.375
  4. 2300
  5. False
  6. True
  7. False
  8. 1 kilowatt-hour (kWh)
  9. 150
  10. motor
  11. 0.3
  12. 0.25
  13. 5 %
  14. 20
  15. 2.3
  16. 4
  17. 0.4
  18. an LED lamp
  19. False
  20. the flow of water
  21. 10
  22. 20
  23. capacitor
  24. brown-yellow-brown
  25. 0.1
  26. a motor
  27. energy used each second
  28. 11.75
  29. wastes electricity
  30. R = V ÷ I
  31. light-emitting diode
  32. 1.5
  33. 400
  34. 3800
  35. 8.8
  36. 5
  37. 4.5
  38. True
  39. gets smaller
  40. less than either one

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