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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 335 · 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 0.375 W device works on 1.5 V. What current does it take (in amperes)? =
  2. 2.📏 Which unit measures current? (a) watt (W) (b) volt (V) (c) ampere (A) (d) ohm (Ω)
  3. 3.🔺 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
  4. 4.🔺 A current of 1.5 A flows when 22.5 V is joined across a resistor. What is its resistance (in ohms)?
  5. 5.📏 Which unit measures power? (a) watt (W) (b) ohm (Ω) (c) ampere (A) (d) volt (V)
  6. 6.💡 Does it save or waste electricity to close the fridge quickly? (a) wastes electricity (b) saves electricity
  7. 7.True or false: to run fans in empty rooms saves electricity. (a) True (b) False
  8. 8.📏 Which unit measures the push of a cell? (a) volt (V) (b) watt (W) (c) ampere (A) (d) ohm (Ω)
  9. 9.🔺 A current of 3 A flows through a 4 Ω resistor. What is the voltage across it (in volts)? =
  10. 10.💡 On an LED, is the longer leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
  11. 11.📏 Which unit measures how much a part resists? (a) volt (V) (b) ohm (Ω) (c) watt (W) (d) ampere (A)
  12. 12.⚡ Which formula gives electric power? (a) P = V × I (b) P = I ÷ V (c) P = V + I (d) P = V ÷ I
  13. 13.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 7200 Ω resistor? (a) violet-red-red (b) red-violet-red (c) violet-red-brown (d) violet-red-orange
  14. 14.🔺 A current of 0.1 A flows through an 8 Ω resistor. What is the voltage across it (in volts)? =
  15. 15.🧩 Which part changes electrical energy into movement? (a) a motor (b) a resistor (c) a fuse (d) an LED
  16. 16.🌈 A resistor has the colour bands violet, red, orange. What is its value in kilo-ohms (kΩ)? =
  17. 17.🔺 A current of 10 mA flows through a 150 Ω resistor. What is the voltage across it (in volts)? =
  18. 18.🧾 A 2000 W appliance runs for 6 hours. How many units (kWh) of electricity does it use? =
  19. 19.Which of these is measured in volts (V)? (a) voltage (b) current (c) power (d) energy used each second
  20. 20.💡 On an LED, is the shorter leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
  21. 21.📏 How many milliamperes (mA) make 1 ampere? (a) 60 (b) 1000 (c) 10 (d) 100
  22. 22.🔺 A current of 50 mA flows when 5 V is joined across a resistor. What is its resistance (in ohms)?
  23. 23.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 25000 Ω resistor? (a) green-red-orange (b) red-green-yellow (c) red-green-red (d) red-green-orange
  24. 24.What does a resistor do? (a) makes a beeping sound (b) blows if current is high (c) senses how hot it is (d) limits the current
  25. 25.🧮 Adding another resistor in series makes the total resistance … (a) bigger (b) smaller (c) stay the same (d) zero
  26. 26.🌈 A resistor has the colour bands yellow, black, red. What is its value in kilo-ohms (kΩ)? =
  27. 27.🔺 A current of 2 A flows when 8 V is joined across a resistor. What is its resistance (in ohms)?
  28. 28.🔺 A current of 0.1 A flows through a 5 Ω resistor. What is the voltage across it (in volts)? =
  29. 29.🔺 A current of 20 mA flows through a 220 Ω resistor. What is the voltage across it (in volts)? =
  30. 30.📏 How many watts (W) is 0.4 kW?
  31. 31.⚡ A device works on 9 V and takes 0.25 A. What is its power (in watts)? =
  32. 32.🔺 A current of 10 mA flows through a 120 Ω resistor. What is the voltage across it (in volts)? =
  33. 33.🧾 A 40 W filament bulb is swapped for a 6 W LED lamp that gives about the same light. Both would run for 4 hours. How many watt-hours (Wh) are saved?
  34. 34.🔺 In the V-I-R triangle, how do we find R? (a) R = V × I (b) R = I ÷ V (c) R = V + I (d) R = V ÷ I
  35. 35.True or false: a resistor makes things spin. (a) False (b) True
  36. 36.🔺 A current of 1.5 A flows through a 10 Ω resistor. What is the voltage across it (in volts)? =
  37. 37.🔺 A current of 1 A flows through a 2 Ω resistor. What is the voltage across it (in volts)? =
  38. 38.🧮 Five equal 25 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  39. 39.🧮 Resistors of 150 Ω and 20 Ω are joined in series. What is the total resistance (in ohms)?
  40. 40.🌈 A gold fourth band on a resistor means the value may be off by … (a) 50 % (b) 0 % (c) 25 % (d) 5 %

Answer key

  1. 0.25
  2. ampere (A)
  3. V = I × R
  4. 15
  5. watt (W)
  6. saves electricity
  7. False
  8. volt (V)
  9. 12
  10. anode (+)
  11. ohm (Ω)
  12. P = V × I
  13. violet-red-red
  14. 0.8
  15. a motor
  16. 72
  17. 1.5
  18. 12
  19. voltage
  20. cathode (−)
  21. 1000
  22. 100
  23. red-green-orange
  24. limits the current
  25. bigger
  26. 4
  27. 4
  28. 0.5
  29. 4.4
  30. 400
  31. 2.25
  32. 1.2
  33. 136
  34. R = V ÷ I
  35. False
  36. 15
  37. 2
  38. 5
  39. 170
  40. 5 %

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