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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 104 · 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 0.5 A flows when 3 V is joined across a resistor. What is its resistance (in ohms)?
  2. 2.🧾 Which lamp gives the same light for the least power? (a) an LED lamp (b) a candle (c) a filament bulb (d) an oil lamp
  3. 3.True or false: to leave the TV on standby saves electricity. (a) True (b) False
  4. 4.⚡ A 4.5 W device works on 1.5 V. What current does it take (in amperes)? =
  5. 5.🔺 A current of 1 A flows through a 12 Ω resistor. What is the voltage across it (in volts)? =
  6. 6.🌈 In the resistor colour code, which number does brown stand for?
  7. 7.🧾 One “unit” on an electricity bill is … (a) 1 ampere (b) 1 kilowatt-hour (kWh) (c) 1 watt (d) 1 volt
  8. 8.🧮 A 220 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)?
  9. 9.What does a transistor do? (a) stores a little charge (b) makes things spin (c) boosts a small signal (d) limits the current
  10. 10.🧩 Which part changes electrical energy into movement? (a) an LED (b) a motor (c) a resistor (d) a fuse
  11. 11.📏 How many kilowatts (kW) is 400 W? =
  12. 12.🔺 A current of 1 A flows through a 20 Ω resistor. What is the voltage across it (in volts)? =
  13. 13.⚡ A home appliance on the 230 V mains takes 1.5 A. What is its power (in watts)?
  14. 14.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) gets smaller (b) gets bigger (c) becomes zero (d) stays the same
  15. 15.🔺 A current of 2.5 A flows when 12.5 V is joined across a resistor. What is its resistance (in ohms)?
  16. 16.🔺 A current of 2 A flows through a 3 Ω resistor. What is the voltage across it (in volts)? =
  17. 17.🧮 Adding another resistor in series makes the total resistance … (a) stay the same (b) bigger (c) zero (d) smaller
  18. 18.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 56 Ω resistor? (a) green-blue-brown (b) blue-blue-black (c) blue-green-black (d) green-blue-black
  19. 19.🔺 In the V-I-R triangle, how do we find R? (a) R = I ÷ V (b) R = V ÷ I (c) R = V + I (d) R = V × I
  20. 20.⚡ A home appliance on the 230 V mains takes 2 A. What is its power (in watts)?
  21. 21.🧾 A 40 W filament bulb is swapped for a 6 W LED lamp that gives about the same light. Both would run for 1 hour. How many watt-hours (Wh) are saved?
  22. 22.🔺 A current of 2 A flows through a 15 Ω resistor. What is the voltage across it (in volts)? =
  23. 23.🧮 Two resistors in parallel give a total that is … (a) less than either one (b) their sum (c) more than either one (d) always zero
  24. 24.📏 Which unit measures the flow of charge? (a) watt (W) (b) ampere (A) (c) volt (V) (d) ohm (Ω)
  25. 25.💡 On an LED, is the longer leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
  26. 26.⚡ Which formula gives electric power? (a) P = I ÷ V (b) P = V × I (c) P = V ÷ I (d) P = V + I
  27. 27.🌈 A resistor has the colour bands grey, green, black. What is its value (in ohms)?
  28. 28.🧮 Three equal 15 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  29. 29.Which of these is measured in watts (W)? (a) power (b) the push of a cell (c) current (d) voltage
  30. 30.🌈 A resistor has the colour bands orange, green, red. What is its value in kilo-ohms (kΩ)? =
  31. 31.🔺 A current of 0.5 A flows when 1.5 V is joined across a resistor. What is its resistance (in ohms)?
  32. 32.Which of these saves electricity? (a) use old filament bulbs (b) leave the TV on standby (c) leave fridge door open (d) use daylight to read
  33. 33.🔍 Which is the odd one out? (a) iron one shirt at a time (b) unplug idle chargers (c) close the fridge quickly (d) use daylight to read
  34. 34.🧮 A 150 Ω resistor is joined in series with two equal 10 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
  35. 35.🌈 A resistor has the colour bands blue, black, brown. What is its value (in ohms)?
  36. 36.🧮 Two equal 1000 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  37. 37.🌈 A gold fourth band on a resistor means the value may be off by … (a) 5 % (b) 50 % (c) 0 % (d) 25 %
  38. 38.📏 How many ohms make 1 kilo-ohm (kΩ)? (a) 1000 (b) 10 (c) 1024 (d) 100
  39. 39.🌈 A resistor has the colour bands violet, violet, red. What is its value in kilo-ohms (kΩ)? =
  40. 40.⚡ A device works on 3 V and takes 0.5 A. What is its power (in watts)? =

Answer key

  1. 6
  2. an LED lamp
  3. False
  4. 3
  5. 12
  6. 1
  7. 1 kilowatt-hour (kWh)
  8. 385
  9. boosts a small signal
  10. a motor
  11. 0.4
  12. 20
  13. 345
  14. gets smaller
  15. 5
  16. 6
  17. bigger
  18. green-blue-black
  19. R = V ÷ I
  20. 460
  21. 34
  22. 30
  23. less than either one
  24. ampere (A)
  25. anode (+)
  26. P = V × I
  27. 85
  28. 5
  29. power
  30. 3.5
  31. 3
  32. use daylight to read
  33. iron one shirt at a time
  34. 155
  35. 600
  36. 500
  37. 5 %
  38. 1000
  39. 7.7
  40. 1.5

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