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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 671 · 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 current of 40 mA flows through a 100 Ω resistor. What is the voltage across it (in volts)? =
  2. 2.🔺 A current of 2 A flows through a 5 Ω resistor. What is the voltage across it (in volts)? =
  3. 3.📏 How many kilo-ohms (kΩ) is 3400 Ω? =
  4. 4.💡 What happens if an LED is put in backwards? (a) it does not light (b) it changes colour (c) it lights brighter (d) it makes a sound
  5. 5.💡 On an LED, is the shorter leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
  6. 6.🌈 In the resistor colour code, which number does orange stand for?
  7. 7.🧩 Which component stores a little charge? (a) diode (b) resistor (c) fuse (d) capacitor
  8. 8.🧮 Resistors of 100 Ω and 33 Ω are joined in series. What is the total resistance (in ohms)?
  9. 9.🌈 In the resistor colour code, which number does red stand for?
  10. 10.⚡ A device works on 12 V and takes 3 A. What is its power (in watts)? =
  11. 11.🌈 Which band is read first on a resistor? (a) the widest gap (b) any band (c) the gold band (d) the one nearest an end
  12. 12.🔺 A 6 V supply is joined across a 300 Ω resistor. What current flows (in milliamperes, mA)?
  13. 13.🧮 A 12 V battery is joined to 12 Ω and 12 Ω resistors in series. What current flows (in amperes)? =
  14. 14.🧾 One “unit” on an electricity bill is … (a) 1 volt (b) 1 watt (c) 1 ampere (d) 1 kilowatt-hour (kWh)
  15. 15.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) gets bigger (b) gets smaller (c) becomes zero (d) stays the same
  16. 16.🔺 A current of 0.25 A flows through a 6 Ω resistor. What is the voltage across it (in volts)? =
  17. 17.⚡ 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
  18. 18.🔺 A 2.5 V supply is joined across a 100 Ω resistor. What current flows (in milliamperes, mA)?
  19. 19.💡 Does it save or waste electricity to leave fridge door open? (a) wastes electricity (b) saves electricity
  20. 20.🔺 A current of 40 mA flows through a 120 Ω resistor. What is the voltage across it (in volts)? =
  21. 21.🔺 A current of 3 A flows when 30 V is joined across a resistor. What is its resistance (in ohms)?
  22. 22.💡 Does it save or waste electricity to use LED lamps? (a) saves electricity (b) wastes electricity
  23. 23.🔺 A current of 25 mA flows through a 100 Ω resistor. What is the voltage across it (in volts)? =
  24. 24.🧾 A 200 W appliance runs for 8 hours. How many units (kWh) of electricity does it use? =
  25. 25.🔺 A current of 0.5 A flows when 2 V is joined across a resistor. What is its resistance (in ohms)?
  26. 26.🔺 A current of 2.5 A flows through a 4 Ω resistor. What is the voltage across it (in volts)? =
  27. 27.🔺 A current of 20 mA flows through a 120 Ω resistor. What is the voltage across it (in volts)? =
  28. 28.🧮 Two resistors in parallel give a total that is … (a) always zero (b) more than either one (c) less than either one (d) their sum
  29. 29.🧮 Five equal 125 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  30. 30.🧮 A 3.5 V battery is joined to 10 Ω and 4 Ω resistors in series. What current flows (in amperes)? =
  31. 31.⚡ A home appliance on the 230 V mains takes 1.5 A. What is its power (in watts)?
  32. 32.📏 In the water-pipe picture of a circuit, current is like … (a) a narrow pipe (b) the water pressure (c) the flow of water (d) the pipe colour
  33. 33.True or false: how much a part resists is measured in amperes (A). (a) True (b) False
  34. 34.🧮 Adding another resistor in series makes the total resistance … (a) smaller (b) zero (c) stay the same (d) bigger
  35. 35.🧾 A 1500 W appliance runs for 5 hours. How many units (kWh) of electricity does it use? =
  36. 36.⚡ A 36 W device works on 12 V. What current does it take (in amperes)? =
  37. 37.🔺 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
  38. 38.🌈 In the resistor colour code, which number does grey stand for?
  39. 39.🔺 In the V-I-R triangle, how do we find I? (a) I = V × R (b) I = V + R (c) I = V ÷ R (d) I = R ÷ V
  40. 40.🌈 A gold fourth band on a resistor means the value may be off by … (a) 25 % (b) 5 % (c) 50 % (d) 0 %

Answer key

  1. 4
  2. 10
  3. 3.4
  4. it does not light
  5. cathode (−)
  6. 3
  7. capacitor
  8. 133
  9. 2
  10. 36
  11. the one nearest an end
  12. 20
  13. 0.5
  14. 1 kilowatt-hour (kWh)
  15. gets smaller
  16. 1.5
  17. energy used each second
  18. 25
  19. wastes electricity
  20. 4.8
  21. 10
  22. saves electricity
  23. 2.5
  24. 1.6
  25. 4
  26. 10
  27. 2.4
  28. less than either one
  29. 25
  30. 0.25
  31. 345
  32. the flow of water
  33. False
  34. bigger
  35. 7.5
  36. 3
  37. V = I × R
  38. 8
  39. I = V ÷ R
  40. 5 %

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