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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 883 · 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.🔺 In the V-I-R triangle, how do we find V? (a) V = I ÷ R (b) V = R ÷ I (c) V = I + R (d) V = I × R
  2. 2.⚡ A device works on 1.5 V and takes 1 A. What is its power (in watts)? =
  3. 3.🔺 A current of 0.25 A flows through a 4 Ω resistor. What is the voltage across it (in volts)? =
  4. 4.Which of these saves electricity? (a) unplug idle chargers (b) iron one shirt at a time (c) leave fridge door open (d) run fans in empty rooms
  5. 5.🌈 A resistor has the colour bands brown, black, brown. What is its value (in ohms)?
  6. 6.💡 A red LED uses 2 V and should get 10 mA. It runs from a 12 V supply. What resistor (in ohms) is needed in series?
  7. 7.💡 On an LED, is the leg by the flat edge the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
  8. 8.🌈 A resistor has the colour bands violet, white, orange. What is its value in kilo-ohms (kΩ)? =
  9. 9.True or false: how much a part resists is measured in ohms (Ω). (a) False (b) True
  10. 10.⚡ A device works on 5 V and takes 0.5 A. What is its power (in watts)? =
  11. 11.💡 Does it save or waste electricity to iron one shirt at a time? (a) saves electricity (b) wastes electricity
  12. 12.⚡ A device works on 1.5 V and takes 2 A. What is its power (in watts)? =
  13. 13.Which of these saves electricity? (a) use daylight to read (b) use old filament bulbs (c) run fans in empty rooms (d) leave the TV on standby
  14. 14.🔺 A current of 0.25 A flows when 3.75 V is joined across a resistor. What is its resistance (in ohms)?
  15. 15.🔺 A current of 10 mA flows through a 200 Ω resistor. What is the voltage across it (in volts)? =
  16. 16.🧮 Resistors of 22 Ω, 33 Ω and 330 Ω are joined in series. What is the total resistance (in ohms)?
  17. 17.💡 On an LED, is the longer leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
  18. 18.🧮 Adding another resistor in series makes the total resistance … (a) smaller (b) zero (c) bigger (d) stay the same
  19. 19.⚡ A 12 W device works on 12 V. What current does it take (in amperes)? =
  20. 20.🌈 A resistor has the colour bands green, black, red. What is its value (in ohms)?
  21. 21.⚡ A home appliance on the 230 V mains takes 1.5 A. What is its power (in watts)?
  22. 22.📏 How many milliamperes (mA) make 1 ampere? (a) 10 (b) 100 (c) 1000 (d) 60
  23. 23.🔺 A current of 25 mA flows when 7.5 V is joined across a resistor. What is its resistance (in ohms)?
  24. 24.💡 An LED is joined to a 5 V battery with no resistor; the leg next to the flat edge of its rim goes to the − side. What happens? (a) does not light (b) lights up (c) may burn out
  25. 25.What does a potentiometer do? (a) turns a fan or wheels (b) is a resistance knob (c) glows using little power (d) stores a little charge
  26. 26.Which of these is measured in watts (W)? (a) voltage (b) power (c) the flow of charge (d) resistance
  27. 27.⚡ Which formula gives electric power? (a) P = V + I (b) P = I ÷ V (c) P = V × I (d) P = V ÷ I
  28. 28.🔺 An 8 V supply is joined across a 400 Ω resistor. What current flows (in milliamperes, mA)?
  29. 29.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 35 Ω resistor? (a) orange-green-black (b) green-orange-black (c) orange-green-brown (d) yellow-green-black
  30. 30.🧮 Two equal 470 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  31. 31.💡 An LED is joined to a 9 V battery with no resistor; the leg next to the flat edge of its rim goes to the − side. What happens? (a) does not light (b) lights up (c) may burn out
  32. 32.🔺 A current of 1.5 A flows through a 15 Ω resistor. What is the voltage across it (in volts)? =
  33. 33.⚡ A home appliance on the 230 V mains takes 4 A. What is its power (in watts)?
  34. 34.🔺 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
  35. 35.💡 On an LED, is the shorter leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
  36. 36.🔺 A current of 0.25 A flows through a 6 Ω resistor. What is the voltage across it (in volts)? =
  37. 37.🔍 Which is the odd one out? (a) iron one shirt at a time (b) unplug idle chargers (c) use LED lamps (d) close the fridge quickly
  38. 38.📏 How many amperes (A) is 580 mA? =
  39. 39.🌈 A gold fourth band on a resistor means the value may be off by … (a) 50 % (b) 0 % (c) 25 % (d) 5 %
  40. 40.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 120 Ω resistor? (a) brown-red-red (b) brown-red-brown (c) brown-red-black (d) red-brown-brown

Answer key

  1. V = I × R
  2. 1.5
  3. 1
  4. unplug idle chargers
  5. 100
  6. 1000
  7. cathode (−)
  8. 79
  9. True
  10. 2.5
  11. wastes electricity
  12. 3
  13. use daylight to read
  14. 15
  15. 2
  16. 385
  17. anode (+)
  18. bigger
  19. 1
  20. 5000
  21. 345
  22. 1000
  23. 300
  24. may burn out
  25. is a resistance knob
  26. power
  27. P = V × I
  28. 20
  29. orange-green-black
  30. 235
  31. may burn out
  32. 22.5
  33. 920
  34. I = V ÷ R
  35. cathode (−)
  36. 1.5
  37. iron one shirt at a time
  38. 0.58
  39. 5 %
  40. brown-red-brown

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