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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 948 · 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.🌈 Which band is read first on a resistor? (a) the gold band (b) the widest gap (c) any band (d) the one nearest an end
  2. 2.⚡ A home appliance on the 230 V mains takes 2 A. What is its power (in watts)?
  3. 3.True or false: current is measured in volts (V). (a) True (b) False
  4. 4.💡 On an LED, is the leg by the flat edge the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
  5. 5.🧮 Resistors of 100 Ω and 330 Ω are joined in series. What is the total resistance (in ohms)?
  6. 6.⚡ Power tells us … (a) the size of a cell (b) energy used each second (c) the length of a wire (d) the colour of light
  7. 7.📏 Voltmeter or ammeter: which one measures voltage? (a) ammeter (b) voltmeter
  8. 8.🔺 A current of 0.5 A flows through a 20 Ω resistor. What is the voltage across it (in volts)? =
  9. 9.True or false: a motor turns a fan or wheels. (a) False (b) True
  10. 10.💡 Does it save or waste electricity to set the AC to 24 °C? (a) wastes electricity (b) saves electricity
  11. 11.🔺 A current of 10 mA flows through a 100 Ω resistor. What is the voltage across it (in volts)? =
  12. 12.True or false: power is measured in watts (W). (a) True (b) False
  13. 13.What does a fuse do? (a) blows if current is high (b) turns a fan or wheels (c) makes things spin (d) senses how hot it is
  14. 14.🧮 Resistors of 33 Ω and 47 Ω are joined in series. What is the total resistance (in ohms)?
  15. 15.🔺 A 5 V supply is joined across a 20 Ω resistor. What current flows (in amperes)? =
  16. 16.True or false: on an LED, the shorter leg is the anode (+). (a) False (b) True
  17. 17.🔺 A current of 0.5 A flows when 7.5 V is joined across a resistor. What is its resistance (in ohms)?
  18. 18.🔺 A current of 2.5 A flows through a 4 Ω resistor. What is the voltage across it (in volts)? =
  19. 19.🧮 Resistors of 220 Ω, 50 Ω, 220 Ω and 33 Ω are joined in series. What is the total resistance (in ohms)?
  20. 20.⚡ A 0.5 W device works on 5 V. What current does it take (in amperes)? =
  21. 21.🧾 One “unit” on an electricity bill is … (a) 1 volt (b) 1 ampere (c) 1 kilowatt-hour (kWh) (d) 1 watt
  22. 22.🧮 A 20 Ω resistor is joined in series with two equal 330 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
  23. 23.Which of these is measured in watts (W)? (a) the flow of charge (b) how much a part resists (c) current (d) energy used each second
  24. 24.🌈 A resistor has the colour bands yellow, black, brown. What is its value (in ohms)?
  25. 25.💡 What happens if an LED is put in backwards? (a) it makes a sound (b) it does not light (c) it lights brighter (d) it changes colour
  26. 26.True or false: to unplug idle chargers wastes electricity. (a) False (b) True
  27. 27.💡 An LED is joined to a 9 V battery through a 220 Ω 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
  28. 28.📏 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
  29. 29.🧮 Resistors of 10 Ω and 10 Ω are joined in series. What is the total resistance (in ohms)?
  30. 30.True or false: on an LED, the round-side leg is the cathode (−). (a) True (b) False
  31. 31.🌈 A gold fourth band on a resistor means the value may be off by … (a) 0 % (b) 25 % (c) 5 % (d) 50 %
  32. 32.⚡ A device works on 5 V and takes 1 A. What is its power (in watts)? =
  33. 33.🌈 A resistor has the colour bands red, red, orange. What is its value (in ohms)?
  34. 34.🌈 A resistor has the colour bands yellow, white, orange. What is its value in kilo-ohms (kΩ)? =
  35. 35.⚡ A 2.4 W device works on 24 V. What current does it take (in amperes)? =
  36. 36.🔺 A current of 25 mA flows when 2.5 V is joined across a resistor. What is its resistance (in ohms)?
  37. 37.🔺 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
  38. 38.💡 A blue LED uses 3 V and should get 20 mA. It runs from a 9 V supply. What resistor (in ohms) is needed in series?
  39. 39.🔍 Which is the odd one out? (a) unplug idle chargers (b) switch off empty rooms (c) use daylight to read (d) run fans in empty rooms
  40. 40.True or false: to close the fridge quickly wastes electricity. (a) False (b) True

Answer key

  1. the one nearest an end
  2. 460
  3. False
  4. cathode (−)
  5. 430
  6. energy used each second
  7. voltmeter
  8. 10
  9. True
  10. saves electricity
  11. 1
  12. True
  13. blows if current is high
  14. 80
  15. 0.25
  16. False
  17. 15
  18. 10
  19. 523
  20. 0.1
  21. 1 kilowatt-hour (kWh)
  22. 185
  23. energy used each second
  24. 400
  25. it does not light
  26. False
  27. lights up
  28. the flow of water
  29. 20
  30. False
  31. 5 %
  32. 5
  33. 22000
  34. 49
  35. 0.1
  36. 100
  37. I = V ÷ R
  38. 300
  39. run fans in empty rooms
  40. False

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