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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 102 · 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.🔺 A 1.6 V supply is joined across an 8 Ω resistor. What current flows (in amperes)? =
  2. 2.🧩 Which component lets current go one way? (a) LDR (b) capacitor (c) thermistor (d) diode
  3. 3.💡 An LED is joined to a 3 V battery through a 330 Ω resistor; the leg next to the flat edge of its rim goes to the − side. What happens? (a) may burn out (b) does not light (c) lights up
  4. 4.⚡ Which formula gives electric power? (a) P = V + I (b) P = V ÷ I (c) P = I ÷ V (d) P = V × I
  5. 5.🌈 A gold fourth band on a resistor means the value may be off by … (a) 50 % (b) 25 % (c) 5 % (d) 0 %
  6. 6.📏 Which unit measures resistance? (a) volt (V) (b) watt (W) (c) ohm (Ω) (d) ampere (A)
  7. 7.🌈 A resistor has the colour bands orange, black, brown. What is its value (in ohms)?
  8. 8.🔺 A current of 10 mA flows through a 400 Ω resistor. What is the voltage across it (in volts)? =
  9. 9.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) stays the same (b) becomes zero (c) gets smaller (d) gets bigger
  10. 10.True or false: current is measured in volts (V). (a) True (b) False
  11. 11.🧮 Four equal 40 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  12. 12.🔺 A 1.2 V supply is joined across a 12 Ω resistor. What current flows (in amperes)? =
  13. 13.🧾 A 100 W filament bulb is swapped for a 15 W LED lamp that gives about the same light. Both would run for 9 hours. How many watt-hours (Wh) are saved?
  14. 14.🔺 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
  15. 15.🧮 Two resistors in parallel give a total that is … (a) their sum (b) more than either one (c) less than either one (d) always zero
  16. 16.🧮 Three equal 15 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  17. 17.📏 Voltmeter or ammeter: which one measures current? (a) voltmeter (b) ammeter
  18. 18.True or false: on an LED, the round-side leg is the cathode (−). (a) True (b) False
  19. 19.True or false: to leave fridge door open saves electricity. (a) False (b) True
  20. 20.⚡ Power tells us … (a) the length of a wire (b) the colour of light (c) the size of a cell (d) energy used each second
  21. 21.⚡ A device works on 5 V and takes 1.5 A. What is its power (in watts)? =
  22. 22.What does a capacitor do? (a) senses how bright it is (b) is a resistance knob (c) glows using little power (d) stores a little charge
  23. 23.🔺 In the V-I-R triangle, how do we find R? (a) R = V × I (b) R = V ÷ I (c) R = I ÷ V (d) R = V + I
  24. 24.🧩 A capacitor in a circuit can … (a) make light (b) spin a wheel (c) measure heat (d) store charge briefly
  25. 25.🔺 A current of 10 mA flows through a 120 Ω resistor. What is the voltage across it (in volts)? =
  26. 26.True or false: a motor makes things spin. (a) True (b) False
  27. 27.🌈 A resistor has the colour bands green, blue, black. What is its value (in ohms)?
  28. 28.🔺 A current of 20 mA flows when 3 V is joined across a resistor. What is its resistance (in ohms)?
  29. 29.True or false: a resistor has coloured bands. (a) True (b) False
  30. 30.True or false: on an LED, the longer leg is the cathode (−). (a) False (b) True
  31. 31.🌈 A resistor has the colour bands grey, red, red. What is its value in kilo-ohms (kΩ)? =
  32. 32.💡 On an LED, is the round-side leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
  33. 33.🔺 A current of 20 mA flows through a 120 Ω resistor. What is the voltage across it (in volts)? =
  34. 34.💡 Does it save or waste electricity to close the fridge quickly? (a) wastes electricity (b) saves electricity
  35. 35.🧩 Which part changes electrical energy into sound? (a) a capacitor (b) a buzzer (c) a diode (d) a resistor
  36. 36.🔺 A current of 2 A flows through a 3 Ω resistor. What is the voltage across it (in volts)? =
  37. 37.🌈 A resistor has the colour bands blue, white, orange. What is its value (in ohms)?
  38. 38.🔺 A current of 10 mA flows through a 330 Ω resistor. What is the voltage across it (in volts)? =
  39. 39.💡 An LED is joined to a 6 V battery through a 330 Ω resistor; its long leg goes to the + side and its short leg to the − side. What happens? (a) does not light (b) may burn out (c) lights up
  40. 40.📏 In the water-pipe picture of a circuit, voltage is like … (a) the water pressure (b) the water tank lid (c) the tap handle (d) the pipe colour

Answer key

  1. 0.2
  2. diode
  3. lights up
  4. P = V × I
  5. 5 %
  6. ohm (Ω)
  7. 300
  8. 4
  9. gets smaller
  10. False
  11. 10
  12. 0.1
  13. 765
  14. V = I × R
  15. less than either one
  16. 5
  17. ammeter
  18. False
  19. False
  20. energy used each second
  21. 7.5
  22. stores a little charge
  23. R = V ÷ I
  24. store charge briefly
  25. 1.2
  26. True
  27. 56
  28. 150
  29. True
  30. False
  31. 8.2
  32. anode (+)
  33. 2.4
  34. saves electricity
  35. a buzzer
  36. 6
  37. 69000
  38. 3.3
  39. lights up
  40. the water pressure

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