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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 753 · 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 13.5 W device works on 9 V. What current does it take (in amperes)? =
  2. 2.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 2500 Ω resistor? (a) red-green-brown (b) red-green-orange (c) green-red-red (d) red-green-red
  3. 3.🔺 A current of 0.2 A flows when 3 V is joined across a resistor. What is its resistance (in ohms)?
  4. 4.🧮 Adding another resistor in series makes the total resistance … (a) smaller (b) stay the same (c) zero (d) bigger
  5. 5.🔺 A 16.5 V supply is joined across a 330 Ω resistor. What current flows (in milliamperes, mA)?
  6. 6.🧮 Three equal 30 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  7. 7.🌈 In the resistor colour code, which number does white stand for?
  8. 8.⚡ A 0.3 W device works on 1.5 V. What current does it take (in amperes)? =
  9. 9.🌈 A resistor has the colour bands orange, yellow, brown. What is its value (in ohms)?
  10. 10.🧾 One “unit” on an electricity bill is … (a) 1 watt (b) 1 volt (c) 1 kilowatt-hour (kWh) (d) 1 ampere
  11. 11.🌈 A gold fourth band on a resistor means the value may be off by … (a) 25 % (b) 0 % (c) 5 % (d) 50 %
  12. 12.🌈 Which band is read first on a resistor? (a) the gold band (b) the one nearest an end (c) the widest gap (d) any band
  13. 13.True or false: current is measured in amperes (A). (a) True (b) False
  14. 14.Which of these is measured in ohms (Ω)? (a) the flow of charge (b) energy used each second (c) current (d) how much a part resists
  15. 15.📏 Voltmeter or ammeter: which one measures voltage? (a) ammeter (b) voltmeter
  16. 16.🧮 Resistors of 22 Ω, 330 Ω and 50 Ω are joined in series. What is the total resistance (in ohms)?
  17. 17.🔺 A current of 1.5 A flows through a 4 Ω resistor. What is the voltage across it (in volts)? =
  18. 18.🌈 A resistor has the colour bands grey, red, red. What is its value (in ohms)?
  19. 19.📏 How many ohms make 1 kilo-ohm (kΩ)? (a) 1024 (b) 1000 (c) 100 (d) 10
  20. 20.🔺 A current of 0.25 A flows through an 8 Ω resistor. What is the voltage across it (in volts)? =
  21. 21.True or false: on an LED, the longer leg is the anode (+). (a) False (b) True
  22. 22.⚡ A device works on 1.5 V and takes 1 A. What is its power (in watts)? =
  23. 23.What does an LDR do? (a) senses how bright it is (b) senses how hot it is (c) stores a little charge (d) is a resistance knob
  24. 24.💡 A red LED (it uses 2 V) is joined with a 100 Ω resistor to a 3.5 V supply. What current flows (in mA)?
  25. 25.⚡ A home appliance on the 230 V mains takes 1.5 A. What is its power (in watts)?
  26. 26.🧩 Which part changes electrical energy into movement? (a) a fuse (b) a motor (c) a resistor (d) an LED
  27. 27.True or false: the ammeter measures current. (a) True (b) False
  28. 28.🔺 In the V-I-R triangle, how do we find R? (a) R = V × I (b) R = V ÷ I (c) R = V + I (d) R = I ÷ V
  29. 29.🔺 A current of 1 A flows through a 4 Ω resistor. What is the voltage across it (in volts)? =
  30. 30.🔺 In the V-I-R triangle, how do we find V? (a) V = R ÷ I (b) V = I × R (c) V = I + R (d) V = I ÷ R
  31. 31.📏 Which unit measures how much a part resists? (a) volt (V) (b) ohm (Ω) (c) watt (W) (d) ampere (A)
  32. 32.🔺 A 1 V supply is joined across a 10 Ω resistor. What current flows (in amperes)? =
  33. 33.📏 How many kilo-ohms (kΩ) is 4500 Ω? =
  34. 34.📏 How many milliamperes (mA) make 1 ampere? (a) 100 (b) 60 (c) 10 (d) 1000
  35. 35.📏 How many watts (W) is 2.4 kW?
  36. 36.💡 What does LED stand for? (a) light energy dial (b) large electric dial (c) low energy device (d) light-emitting diode
  37. 37.🔺 A current of 0.2 A flows through a 10 Ω resistor. What is the voltage across it (in volts)? =
  38. 38.💡 A red LED uses 2 V and should get 20 mA. It runs from a 5 V supply. What resistor (in ohms) is needed in series?
  39. 39.🧮 A 1.2 V battery is joined to 2 Ω and 10 Ω resistors in series. What current flows (in amperes)? =
  40. 40.🔺 A current of 0.5 A flows through a 2 Ω resistor. What is the voltage across it (in volts)? =

Answer key

  1. 1.5
  2. red-green-red
  3. 15
  4. bigger
  5. 50
  6. 10
  7. 9
  8. 0.2
  9. 340
  10. 1 kilowatt-hour (kWh)
  11. 5 %
  12. the one nearest an end
  13. True
  14. how much a part resists
  15. voltmeter
  16. 402
  17. 6
  18. 8200
  19. 1000
  20. 2
  21. True
  22. 1.5
  23. senses how bright it is
  24. 15
  25. 345
  26. a motor
  27. True
  28. R = V ÷ I
  29. 4
  30. V = I × R
  31. ohm (Ω)
  32. 0.1
  33. 4.5
  34. 1000
  35. 2400
  36. light-emitting diode
  37. 2
  38. 150
  39. 0.1
  40. 1

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