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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 945 · 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 gold fourth band on a resistor means the value may be off by … (a) 50 % (b) 0 % (c) 25 % (d) 5 %
  2. 2.🔺 A current of 3 A flows through a 4 Ω resistor. What is the voltage across it (in volts)? =
  3. 3.🔺 A current of 40 mA flows through a 120 Ω resistor. What is the voltage across it (in volts)? =
  4. 4.⚡ A device works on 12 V and takes 1.5 A. What is its power (in watts)? =
  5. 5.🔺 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
  6. 6.🧮 Resistors of 10 Ω, 68 Ω and 22 Ω are joined in series. What is the total resistance (in ohms)?
  7. 7.🌈 A resistor has the colour bands white, brown, red. What is its value (in ohms)?
  8. 8.💡 Why does an LED need a resistor in series? (a) to limit the current (b) to change its colour (c) to make it brighter (d) to store charge
  9. 9.⚡ Power tells us … (a) the colour of light (b) energy used each second (c) the length of a wire (d) the size of a cell
  10. 10.🔺 A 0.75 V supply is joined across a 3 Ω resistor. What current flows (in amperes)? =
  11. 11.📏 Which unit measures voltage? (a) ohm (Ω) (b) watt (W) (c) ampere (A) (d) volt (V)
  12. 12.True or false: the ammeter measures voltage. (a) False (b) True
  13. 13.💡 On an LED, is the shorter leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
  14. 14.🔺 A current of 2 A flows through a 10 Ω resistor. What is the voltage across it (in volts)? =
  15. 15.📏 How many kilowatts (kW) is 4700 W? =
  16. 16.💡 A red LED uses 2 V and should get 25 mA. It runs from a 6 V supply. What resistor (in ohms) is needed in series?
  17. 17.True or false: to leave fridge door open wastes electricity. (a) True (b) False
  18. 18.🧮 Resistors of 50 Ω and 330 Ω are joined in series. What is the total resistance (in ohms)?
  19. 19.🔺 A current of 0.5 A flows through a 3 Ω resistor. What is the voltage across it (in volts)? =
  20. 20.What does a transistor do? (a) boosts a small signal (b) has coloured bands (c) beeps for an alarm (d) makes a beeping sound
  21. 21.True or false: a fuse makes things spin. (a) False (b) True
  22. 22.📏 How many kilo-ohms (kΩ) is 4200 Ω? =
  23. 23.💡 Does it save or waste electricity to close the fridge quickly? (a) wastes electricity (b) saves electricity
  24. 24.What does a motor do? (a) turns a fan or wheels (b) has coloured bands (c) glows using little power (d) makes a beeping sound
  25. 25.💡 On an LED, is the round-side leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
  26. 26.🧾 One “unit” on an electricity bill is … (a) 1 volt (b) 1 ampere (c) 1 watt (d) 1 kilowatt-hour (kWh)
  27. 27.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 330 Ω resistor? (a) orange-orange-red (b) orange-orange-black (c) orange-orange-brown (d) orange-yellow-brown
  28. 28.Which of these is measured in watts (W)? (a) the push of a cell (b) how much a part resists (c) voltage (d) energy used each second
  29. 29.🔺 A current of 0.1 A flows through a 3 Ω resistor. What is the voltage across it (in volts)? =
  30. 30.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark an 81 Ω resistor? (a) grey-brown-black (b) grey-brown-brown (c) white-brown-black (d) brown-grey-black
  31. 31.🧮 Two equal 40 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  32. 32.💡 A red LED uses 2 V and should get 25 mA. It runs from a 5 V supply. What resistor (in ohms) is needed in series?
  33. 33.🔺 A current of 10 mA flows when 1.2 V is joined across a resistor. What is its resistance (in ohms)?
  34. 34.📏 How many ohms (Ω) is 8.4 kΩ?
  35. 35.🔺 A 1 V supply is joined across a 2 Ω resistor. What current flows (in amperes)? =
  36. 36.What does a motor do? (a) senses how hot it is (b) makes a beeping sound (c) makes things spin (d) is a resistance knob
  37. 37.🧮 Three equal 150 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  38. 38.💡 An LED is joined to a 5 V battery through a 470 Ω resistor; its long leg goes to the + side and its short leg to the − side. What happens? (a) may burn out (b) lights up (c) does not light
  39. 39.Which of these is measured in volts (V)? (a) the push of a cell (b) the flow of charge (c) energy used each second (d) power
  40. 40.⚡ A home appliance on the 230 V mains takes 2 A. What is its power (in watts)?

Answer key

  1. 5 %
  2. 12
  3. 4.8
  4. 18
  5. gets smaller
  6. 100
  7. 9100
  8. to limit the current
  9. energy used each second
  10. 0.25
  11. volt (V)
  12. False
  13. cathode (−)
  14. 20
  15. 4.7
  16. 160
  17. True
  18. 380
  19. 1.5
  20. boosts a small signal
  21. False
  22. 4.2
  23. saves electricity
  24. turns a fan or wheels
  25. anode (+)
  26. 1 kilowatt-hour (kWh)
  27. orange-orange-brown
  28. energy used each second
  29. 0.3
  30. grey-brown-black
  31. 20
  32. 120
  33. 120
  34. 8400
  35. 0.5
  36. makes things spin
  37. 50
  38. lights up
  39. the push of a cell
  40. 460

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