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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 168 · 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.True or false: to switch off empty rooms wastes electricity. (a) False (b) True
  2. 2.📏 Which unit measures power? (a) ohm (Ω) (b) volt (V) (c) watt (W) (d) ampere (A)
  3. 3.⚡ A home appliance on the 230 V mains takes 10 A. What is its power (in watts)?
  4. 4.True or false: energy used each second is measured in watts (W). (a) False (b) True
  5. 5.What does a capacitor do? (a) boosts a small signal (b) makes things spin (c) senses how hot it is (d) stores a little charge
  6. 6.🧩 Which component boosts a small signal? (a) motor (b) resistor (c) LED (d) transistor
  7. 7.⚡ An 18 W device works on 6 V. What current does it take (in amperes)? =
  8. 8.🌈 A resistor has the colour bands brown, white, orange. What is its value in kilo-ohms (kΩ)? =
  9. 9.What does a fuse do? (a) stores a little charge (b) glows using little power (c) is a resistance knob (d) blows if current is high
  10. 10.🧮 A 150 Ω resistor is joined in series with two equal 40 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
  11. 11.🔺 A current of 10 mA flows when 1.2 V is joined across a resistor. What is its resistance (in ohms)?
  12. 12.⚡ Which formula gives electric power? (a) P = V ÷ I (b) P = V + I (c) P = I ÷ V (d) P = V × I
  13. 13.💡 Does it save or waste electricity to leave the TV on standby? (a) wastes electricity (b) saves electricity
  14. 14.🔺 A current of 20 mA flows through a 120 Ω resistor. What is the voltage across it (in volts)? =
  15. 15.True or false: the voltmeter measures current. (a) True (b) False
  16. 16.What does a resistor do? (a) senses how bright it is (b) limits the current (c) stores a little charge (d) is a resistance knob
  17. 17.🔺 A current of 20 mA flows through a 470 Ω resistor. What is the voltage across it (in volts)? =
  18. 18.🧩 Which component glows using little power? (a) diode (b) capacitor (c) LDR (d) LED
  19. 19.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 430 Ω resistor? (a) yellow-orange-brown (b) yellow-orange-red (c) orange-yellow-brown (d) yellow-orange-black
  20. 20.🌈 A resistor has the colour bands brown, black, orange. What is its value in kilo-ohms (kΩ)? =
  21. 21.🔺 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
  22. 22.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 1000 Ω resistor? (a) brown-black-brown (b) brown-black-orange (c) brown-black-red (d) red-brown-red
  23. 23.True or false: a diode smooths a wobbly supply. (a) True (b) False
  24. 24.🔺 A current of 0.2 A flows through a 6 Ω resistor. What is the voltage across it (in volts)? =
  25. 25.⚡ A device works on 5 V and takes 0.2 A. What is its power (in watts)? =
  26. 26.Which of these wastes electricity? (a) use daylight to read (b) unplug idle chargers (c) set the AC to 24 °C (d) iron one shirt at a time
  27. 27.🔺 A current of 0.2 A flows through a 5 Ω resistor. What is the voltage across it (in volts)? =
  28. 28.💡 On an LED, is the longer leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
  29. 29.🧮 Two equal 470 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  30. 30.📏 Voltmeter or ammeter: which one is joined across a part? (a) voltmeter (b) ammeter
  31. 31.⚡ A device works on 24 V and takes 1.5 A. What is its power (in watts)? =
  32. 32.True or false: to use old filament bulbs wastes electricity. (a) True (b) False
  33. 33.📏 How many milliamperes (mA) is 1.46 A?
  34. 34.True or false: voltage is measured in volts (V). (a) False (b) True
  35. 35.True or false: on an LED, the leg by the flat edge is the cathode (−). (a) True (b) False
  36. 36.🔺 A current of 20 mA flows when 5 V is joined across a resistor. What is its resistance (in ohms)?
  37. 37.🔺 A current of 20 mA flows through a 100 Ω resistor. What is the voltage across it (in volts)? =
  38. 38.🔺 A current of 0.25 A flows when 1 V is joined across a resistor. What is its resistance (in ohms)?
  39. 39.📏 Which unit measures resistance? (a) ohm (Ω) (b) watt (W) (c) ampere (A) (d) volt (V)
  40. 40.🧾 A 2000 W appliance runs for 4 hours. How many units (kWh) of electricity does it use? =

Answer key

  1. False
  2. watt (W)
  3. 2300
  4. True
  5. stores a little charge
  6. transistor
  7. 3
  8. 19
  9. blows if current is high
  10. 170
  11. 120
  12. P = V × I
  13. wastes electricity
  14. 2.4
  15. False
  16. limits the current
  17. 9.4
  18. LED
  19. yellow-orange-brown
  20. 10
  21. R = V ÷ I
  22. brown-black-red
  23. False
  24. 1.2
  25. 1
  26. iron one shirt at a time
  27. 1
  28. anode (+)
  29. 235
  30. voltmeter
  31. 36
  32. True
  33. 1460
  34. True
  35. True
  36. 250
  37. 2
  38. 4
  39. ohm (Ω)
  40. 8

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