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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 210 · 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.📏 Voltmeter or ammeter: which one is joined across a part? (a) voltmeter (b) ammeter
  2. 2.🔺 A 4 V supply is joined across an 8 Ω resistor. What current flows (in amperes)? =
  3. 3.📏 Voltmeter or ammeter: which one is joined in series? (a) voltmeter (b) ammeter
  4. 4.🧾 A 60 W filament bulb is swapped for a 9 W LED lamp that gives about the same light. Both would run for 7 hours. How many watt-hours (Wh) are saved?
  5. 5.🧮 A 220 Ω resistor is joined in series with two equal 470 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
  6. 6.⚡ A home appliance on the 230 V mains takes 8 A. What is its power (in watts)?
  7. 7.🧩 Which component is a resistance knob? (a) capacitor (b) thermistor (c) potentiometer (d) diode
  8. 8.⚡ A 2.25 W device works on 9 V. What current does it take (in amperes)? =
  9. 9.⚡ A device works on 6 V and takes 0.2 A. What is its power (in watts)? =
  10. 10.🔺 A current of 20 mA flows when 2.4 V is joined across a resistor. What is its resistance (in ohms)?
  11. 11.True or false: on an LED, the leg by the flat edge is the cathode (−). (a) True (b) False
  12. 12.🔺 A current of 40 mA flows through a 150 Ω resistor. What is the voltage across it (in volts)? =
  13. 13.📏 How many amperes (A) is 430 mA? =
  14. 14.🔺 A current of 50 mA flows when 5 V is joined across a resistor. What is its resistance (in ohms)?
  15. 15.🧩 Which component turns a fan or wheels? (a) thermistor (b) buzzer (c) motor (d) transistor
  16. 16.💡 An LED is joined to a 12 V battery with no resistor; its long leg goes to the + side and its short leg to the − side. What happens? (a) lights up (b) may burn out (c) does not light
  17. 17.🧾 Which lamp gives the same light for the least power? (a) a candle (b) an LED lamp (c) a filament bulb (d) an oil lamp
  18. 18.🔺 A current of 40 mA flows through a 400 Ω resistor. What is the voltage across it (in volts)? =
  19. 19.🧩 Which part changes electrical energy into movement? (a) a resistor (b) a fuse (c) a motor (d) an LED
  20. 20.True or false: the flow of charge is measured in watts (W). (a) False (b) True
  21. 21.What does an LDR do? (a) lets current go one way (b) senses how bright it is (c) blows if current is high (d) makes things spin
  22. 22.🌈 A resistor has the colour bands green, green, red. What is its value (in ohms)?
  23. 23.🌈 A resistor has the colour bands yellow, orange, red. What is its value (in ohms)?
  24. 24.🔺 A 1.6 V supply is joined across an 8 Ω resistor. What current flows (in amperes)? =
  25. 25.🔺 A current of 3 A flows when 18 V is joined across a resistor. What is its resistance (in ohms)?
  26. 26.🌈 A resistor has the colour bands orange, red, black. What is its value (in ohms)?
  27. 27.🧾 One “unit” on an electricity bill is … (a) 1 volt (b) 1 watt (c) 1 ampere (d) 1 kilowatt-hour (kWh)
  28. 28.🧮 Two equal 470 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  29. 29.🔺 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
  30. 30.⚡ Which formula gives electric power? (a) P = V ÷ I (b) P = V × I (c) P = V + I (d) P = I ÷ V
  31. 31.🧩 Which component makes things spin? (a) fuse (b) LED (c) buzzer (d) motor
  32. 32.🔺 A current of 0.1 A flows when 2 V is joined across a resistor. What is its resistance (in ohms)?
  33. 33.🌈 A gold fourth band on a resistor means the value may be off by … (a) 50 % (b) 5 % (c) 25 % (d) 0 %
  34. 34.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 26000 Ω resistor? (a) red-blue-yellow (b) red-blue-red (c) blue-red-orange (d) red-blue-orange
  35. 35.🔺 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
  36. 36.🧩 Which part changes electrical energy into sound? (a) a resistor (b) a capacitor (c) a diode (d) a buzzer
  37. 37.True or false: to use LED lamps wastes electricity. (a) False (b) True
  38. 38.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) gets smaller (b) becomes zero (c) gets bigger (d) stays the same
  39. 39.🌈 A resistor has the colour bands white, green, brown. What is its value (in ohms)?
  40. 40.💡 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?

Answer key

  1. voltmeter
  2. 0.5
  3. ammeter
  4. 357
  5. 455
  6. 1840
  7. potentiometer
  8. 0.25
  9. 1.2
  10. 120
  11. True
  12. 6
  13. 0.43
  14. 100
  15. motor
  16. may burn out
  17. an LED lamp
  18. 16
  19. a motor
  20. False
  21. senses how bright it is
  22. 5500
  23. 4300
  24. 0.2
  25. 6
  26. 32
  27. 1 kilowatt-hour (kWh)
  28. 235
  29. R = V ÷ I
  30. P = V × I
  31. motor
  32. 20
  33. 5 %
  34. red-blue-orange
  35. V = I × R
  36. a buzzer
  37. False
  38. gets smaller
  39. 950
  40. 150

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