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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 954 · 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.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 7300 Ω resistor? (a) violet-orange-orange (b) orange-violet-red (c) violet-orange-red (d) violet-orange-brown
  2. 2.🧮 A 220 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)?
  3. 3.🧮 Five equal 500 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  4. 4.📏 In the water-pipe picture of a circuit, resistance is like … (a) a bigger tank (b) the water pressure (c) a narrow pipe (d) the flow of water
  5. 5.🔺 A current of 10 mA flows through a 470 Ω resistor. What is the voltage across it (in volts)? =
  6. 6.⚡ Power tells us … (a) the colour of light (b) the size of a cell (c) the length of a wire (d) energy used each second
  7. 7.🔺 In the V-I-R triangle, how do we find I? (a) I = V + R (b) I = R ÷ V (c) I = V ÷ R (d) I = V × R
  8. 8.🧮 Four equal 100 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  9. 9.True or false: on an LED, the round-side leg is the anode (+). (a) True (b) False
  10. 10.🌈 A resistor has the colour bands red, green, orange. What is its value (in ohms)?
  11. 11.🧮 Two equal 470 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  12. 12.🧩 Which component boosts a small signal? (a) capacitor (b) potentiometer (c) LED (d) transistor
  13. 13.🧩 Which component makes things spin? (a) motor (b) diode (c) potentiometer (d) LDR
  14. 14.True or false: a thermistor senses how hot it is. (a) True (b) False
  15. 15.📏 Which unit measures the push of a cell? (a) ohm (Ω) (b) ampere (A) (c) watt (W) (d) volt (V)
  16. 16.🧩 Which component senses how bright it is? (a) thermistor (b) resistor (c) buzzer (d) LDR
  17. 17.🔺 In the V-I-R triangle, how do we find V? (a) V = I ÷ R (b) V = I × R (c) V = R ÷ I (d) V = I + R
  18. 18.💡 An LED is joined to a 9 V battery with no 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
  19. 19.🌈 A resistor has the colour bands white, red, black. What is its value (in ohms)?
  20. 20.True or false: the flow of charge is measured in amperes (A). (a) False (b) True
  21. 21.⚡ Which formula gives electric power? (a) P = V + I (b) P = V ÷ I (c) P = V × I (d) P = I ÷ V
  22. 22.True or false: to close the fridge quickly saves electricity. (a) True (b) False
  23. 23.🧮 A 150 Ω resistor is joined in series with two equal 20 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
  24. 24.📏 How many ohms make 1 kilo-ohm (kΩ)? (a) 1024 (b) 1000 (c) 100 (d) 10
  25. 25.True or false: a resistor has coloured bands. (a) False (b) True
  26. 26.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark an 87000 Ω resistor? (a) violet-grey-orange (b) grey-violet-red (c) grey-violet-orange (d) grey-violet-yellow
  27. 27.True or false: a motor turns a fan or wheels. (a) False (b) True
  28. 28.💡 On an LED, is the longer leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
  29. 29.⚡ A 24 W device works on 24 V. What current does it take (in amperes)? =
  30. 30.💡 Why does an LED need a resistor in series? (a) to make it brighter (b) to change its colour (c) to store charge (d) to limit the current
  31. 31.True or false: on an LED, the shorter leg is the anode (+). (a) False (b) True
  32. 32.💡 On an LED, is the round-side leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
  33. 33.True or false: voltage is measured in amperes (A). (a) True (b) False
  34. 34.🔺 A current of 20 mA flows through a 100 Ω resistor. What is the voltage across it (in volts)? =
  35. 35.True or false: the ammeter measures voltage. (a) True (b) False
  36. 36.⚡ A device works on 12 V and takes 0.25 A. What is its power (in watts)? =
  37. 37.💡 Does it save or waste electricity to leave fridge door open? (a) saves electricity (b) wastes electricity
  38. 38.💡 Does it save or waste electricity to close the fridge quickly? (a) wastes electricity (b) saves electricity
  39. 39.What does a diode do? (a) lets current go one way (b) makes things spin (c) beeps for an alarm (d) is a resistance knob
  40. 40.📏 Voltmeter or ammeter: which one is joined in series? (a) voltmeter (b) ammeter

Answer key

  1. violet-orange-red
  2. 240
  3. 100
  4. a narrow pipe
  5. 4.7
  6. energy used each second
  7. I = V ÷ R
  8. 25
  9. True
  10. 25000
  11. 235
  12. transistor
  13. motor
  14. True
  15. volt (V)
  16. LDR
  17. V = I × R
  18. may burn out
  19. 92
  20. True
  21. P = V × I
  22. True
  23. 160
  24. 1000
  25. True
  26. grey-violet-orange
  27. True
  28. anode (+)
  29. 1
  30. to limit the current
  31. False
  32. anode (+)
  33. False
  34. 2
  35. False
  36. 3
  37. wastes electricity
  38. saves electricity
  39. lets current go one way
  40. ammeter

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