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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 366 · 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.

NameDateTime takenScore ___ / 40
  1. 1.📏 Voltmeter or ammeter: which one measures voltage? (a) ammeter (b) voltmeter
  2. 2.True or false: a thermistor senses how hot it is. (a) False (b) True
  3. 3.True or false: a thermistor blows if current is high. (a) True (b) False
  4. 4.🔺 A current of 10 mA flows through a 330 Ω resistor. What is the voltage across it (in volts)? =
  5. 5.📏 In the water-pipe picture of a circuit, resistance is like … (a) the flow of water (b) a narrow pipe (c) a bigger tank (d) the water pressure
  6. 6.📏 Which unit measures current? (a) watt (W) (b) ohm (Ω) (c) volt (V) (d) ampere (A)
  7. 7.🔺 A current of 0.25 A flows through a 12 Ω resistor. What is the voltage across it (in volts)? =
  8. 8.🧮 Resistors of 330 Ω, 100 Ω, 220 Ω and 10 Ω are joined in series. What is the total resistance (in ohms)?
  9. 9.🔺 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
  10. 10.🧩 Which component lets current go one way? (a) diode (b) buzzer (c) resistor (d) fuse
  11. 11.🌈 In the resistor colour code, which number does white stand for?
  12. 12.True or false: to run fans in empty rooms saves electricity. (a) False (b) True
  13. 13.True or false: on an LED, the longer leg is the anode (+). (a) False (b) True
  14. 14.🧩 Which component beeps for an alarm? (a) fuse (b) buzzer (c) capacitor (d) resistor
  15. 15.🧩 Which component senses how hot it is? (a) LED (b) thermistor (c) capacitor (d) fuse
  16. 16.🌈 A gold fourth band on a resistor means the value may be off by … (a) 25 % (b) 0 % (c) 5 % (d) 50 %
  17. 17.💡 An LED is joined to a 9 V battery through a 220 Ω resistor; its long leg goes to the + side and its short leg to the − side. What happens? (a) may burn out (b) does not light (c) lights up
  18. 18.🔺 A current of 2 A flows through a 12 Ω resistor. What is the voltage across it (in volts)? =
  19. 19.🧮 Resistors of 50 Ω and 47 Ω are joined in series. What is the total resistance (in ohms)?
  20. 20.🧩 Which part changes electrical energy into movement? (a) an LED (b) a resistor (c) a motor (d) a fuse
  21. 21.True or false: to leave fridge door open wastes electricity. (a) True (b) False
  22. 22.What does a transistor do? (a) smooths a wobbly supply (b) has coloured bands (c) is a resistance knob (d) boosts a small signal
  23. 23.🔺 A current of 1.5 A flows through a 20 Ω resistor. What is the voltage across it (in volts)? =
  24. 24.⚡ A home appliance on the 230 V mains takes 1.5 A. What is its power (in watts)?
  25. 25.⚡ A device works on 24 V and takes 0.2 A. What is its power (in watts)? =
  26. 26.⚡ Power tells us … (a) the length of a wire (b) the colour of light (c) energy used each second (d) the size of a cell
  27. 27.🧩 Which component blows if current is high? (a) transistor (b) diode (c) buzzer (d) fuse
  28. 28.💡 A red LED (it uses 2 V) is joined with a 300 Ω resistor to a 3.5 V supply. What current flows (in mA)?
  29. 29.🧮 Two equal 40 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  30. 30.True or false: the ammeter is joined in series. (a) False (b) True
  31. 31.🧾 One “unit” on an electricity bill is … (a) 1 ampere (b) 1 volt (c) 1 watt (d) 1 kilowatt-hour (kWh)
  32. 32.🧮 A 68 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)?
  33. 33.True or false: on an LED, the round-side leg is the anode (+). (a) False (b) True
  34. 34.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 2600 Ω resistor? (a) blue-red-red (b) red-blue-red (c) red-blue-brown (d) red-blue-orange
  35. 35.True or false: to use daylight to read saves electricity. (a) True (b) False
  36. 36.True or false: a resistor senses how hot it is. (a) True (b) False
  37. 37.🔺 A 0.5 V supply is joined across a 2 Ω resistor. What current flows (in amperes)? =
  38. 38.🔺 A current of 2.5 A flows through a 3 Ω resistor. What is the voltage across it (in volts)? =
  39. 39.⚡ A device works on 12 V and takes 0.5 A. What is its power (in watts)? =
  40. 40.🌈 A resistor has the colour bands yellow, grey, red. What is its value in kilo-ohms (kΩ)? =

Answer key

  1. voltmeter
  2. True
  3. False
  4. 3.3
  5. a narrow pipe
  6. ampere (A)
  7. 3
  8. 660
  9. V = I × R
  10. diode
  11. 9
  12. False
  13. True
  14. buzzer
  15. thermistor
  16. 5 %
  17. lights up
  18. 24
  19. 97
  20. a motor
  21. True
  22. boosts a small signal
  23. 30
  24. 345
  25. 4.8
  26. energy used each second
  27. fuse
  28. 5
  29. 20
  30. True
  31. 1 kilowatt-hour (kWh)
  32. 233
  33. True
  34. red-blue-red
  35. True
  36. False
  37. 0.25
  38. 7.5
  39. 6
  40. 4.8

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