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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 302 · 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 resistor colour code, which number does red stand for?
  2. 2.🌈 In the resistor colour code, which number does grey stand for?
  3. 3.🧩 Which component senses how bright it is? (a) buzzer (b) potentiometer (c) motor (d) LDR
  4. 4.💡 A red LED (it uses 2 V) is joined with a 200 Ω resistor to a 5 V supply. What current flows (in mA)?
  5. 5.🔺 A 4.7 V supply is joined across a 470 Ω resistor. What current flows (in milliamperes, mA)?
  6. 6.🔺 A 12.5 V supply is joined across a 500 Ω resistor. What current flows (in milliamperes, mA)?
  7. 7.💡 A blue LED uses 3 V and should get 20 mA. It runs from a 6 V supply. What resistor (in ohms) is needed in series?
  8. 8.🔺 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
  9. 9.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 460 Ω resistor? (a) blue-yellow-brown (b) yellow-blue-brown (c) yellow-blue-black (d) yellow-blue-red
  10. 10.🔺 A current of 1 A flows through a 6 Ω resistor. What is the voltage across it (in volts)? =
  11. 11.🧩 Which part changes electrical energy into movement? (a) a motor (b) an LED (c) a resistor (d) a fuse
  12. 12.⚡ A 4.5 W device works on 9 V. What current does it take (in amperes)? =
  13. 13.🧩 Which component blows if current is high? (a) buzzer (b) potentiometer (c) resistor (d) fuse
  14. 14.🔺 A current of 40 mA flows through a 400 Ω resistor. What is the voltage across it (in volts)? =
  15. 15.⚡ A home appliance on the 230 V mains takes 8 A. What is its power (in watts)?
  16. 16.🔺 A current of 0.25 A flows when 1.5 V is joined across a resistor. What is its resistance (in ohms)?
  17. 17.⚡ A home appliance on the 230 V mains takes 0.5 A. What is its power (in watts)?
  18. 18.What does an LED do? (a) is a resistance knob (b) glows using little power (c) senses how hot it is (d) senses how bright it is
  19. 19.🧮 A 3 V battery is joined to 12 Ω and 3 Ω resistors in series. What current flows (in amperes)? =
  20. 20.📏 Which unit measures current? (a) volt (V) (b) ampere (A) (c) watt (W) (d) ohm (Ω)
  21. 21.True or false: to leave fridge door open saves electricity. (a) True (b) False
  22. 22.📏 How many ohms (Ω) is 3 kΩ?
  23. 23.What does a motor do? (a) senses how hot it is (b) is a resistance knob (c) makes things spin (d) has coloured bands
  24. 24.🌈 A resistor has the colour bands grey, grey, black. What is its value (in ohms)?
  25. 25.True or false: a motor turns a fan or wheels. (a) False (b) True
  26. 26.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) stays the same (b) becomes zero (c) gets bigger (d) gets smaller
  27. 27.💡 On an LED, is the round-side leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
  28. 28.🔺 A current of 40 mA flows when 4.8 V is joined across a resistor. What is its resistance (in ohms)?
  29. 29.🔺 A current of 3 A flows through an 8 Ω resistor. What is the voltage across it (in volts)? =
  30. 30.📏 How many ohms make 1 kilo-ohm (kΩ)? (a) 1000 (b) 1024 (c) 10 (d) 100
  31. 31.⚡ A 6 W device works on 12 V. What current does it take (in amperes)? =
  32. 32.📏 Which unit measures voltage? (a) ohm (Ω) (b) watt (W) (c) volt (V) (d) ampere (A)
  33. 33.⚡ A home appliance on the 230 V mains takes 1.5 A. What is its power (in watts)?
  34. 34.⚡ A device works on 3 V and takes 1 A. What is its power (in watts)? =
  35. 35.🔍 Which is the odd one out? (a) unplug idle chargers (b) set the AC to 24 °C (c) use daylight to read (d) run fans in empty rooms
  36. 36.📏 How many ohms (Ω) is 9.6 kΩ?
  37. 37.🌈 A resistor has the colour bands white, blue, yellow. What is its value in kilo-ohms (kΩ)? =
  38. 38.⚡ A 0.15 W device works on 1.5 V. What current does it take (in amperes)? =
  39. 39.True or false: the ammeter is joined across a part. (a) False (b) True
  40. 40.True or false: a potentiometer is a resistance knob. (a) True (b) False

Answer key

  1. 2
  2. 8
  3. LDR
  4. 15
  5. 10
  6. 25
  7. 150
  8. V = I × R
  9. yellow-blue-brown
  10. 6
  11. a motor
  12. 0.5
  13. fuse
  14. 16
  15. 1840
  16. 6
  17. 115
  18. glows using little power
  19. 0.2
  20. ampere (A)
  21. False
  22. 3000
  23. makes things spin
  24. 88
  25. True
  26. gets smaller
  27. anode (+)
  28. 120
  29. 24
  30. 1000
  31. 0.5
  32. volt (V)
  33. 345
  34. 3
  35. run fans in empty rooms
  36. 9600
  37. 960
  38. 0.1
  39. False
  40. True

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