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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 955 · 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 470 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)?
  2. 2.🧮 Two resistors in parallel give a total that is … (a) more than either one (b) their sum (c) less than either one (d) always zero
  3. 3.🔺 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
  4. 4.🔍 Which is the odd one out? (a) use daylight to read (b) close the fridge quickly (c) leave the TV on standby (d) unplug idle chargers
  5. 5.🧩 Which component makes things spin? (a) fuse (b) LED (c) LDR (d) motor
  6. 6.🔺 A current of 40 mA flows through a 500 Ω resistor. What is the voltage across it (in volts)? =
  7. 7.🧮 Resistors of 20 Ω, 47 Ω and 220 Ω are joined in series. What is the total resistance (in ohms)?
  8. 8.🧮 Adding another resistor in series makes the total resistance … (a) zero (b) stay the same (c) smaller (d) bigger
  9. 9.🔺 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
  10. 10.⚡ A home appliance on the 230 V mains takes 1.5 A. What is its power (in watts)?
  11. 11.🔺 A current of 0.1 A flows when 0.3 V is joined across a resistor. What is its resistance (in ohms)?
  12. 12.💡 What does LED stand for? (a) low energy device (b) large electric dial (c) light energy dial (d) light-emitting diode
  13. 13.🧩 Which component limits the current? (a) LED (b) resistor (c) transistor (d) fuse
  14. 14.🔺 A current of 50 mA flows through a 300 Ω resistor. What is the voltage across it (in volts)? =
  15. 15.🔺 A current of 0.2 A flows through a 3 Ω resistor. What is the voltage across it (in volts)? =
  16. 16.What does a transistor do? (a) makes a beeping sound (b) senses how hot it is (c) boosts a small signal (d) lets current go one way
  17. 17.🌈 A gold fourth band on a resistor means the value may be off by … (a) 50 % (b) 0 % (c) 5 % (d) 25 %
  18. 18.⚡ A device works on 3 V and takes 0.1 A. What is its power (in watts)? =
  19. 19.True or false: the voltmeter measures current. (a) True (b) False
  20. 20.🧮 Resistors of 22 Ω and 50 Ω are joined in series. What is the total resistance (in ohms)?
  21. 21.🔺 A 10 V supply is joined across a 200 Ω resistor. What current flows (in milliamperes, mA)?
  22. 22.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 47000 Ω resistor? (a) violet-yellow-orange (b) yellow-violet-red (c) yellow-violet-yellow (d) yellow-violet-orange
  23. 23.What does a diode do? (a) lets current go one way (b) blows if current is high (c) boosts a small signal (d) has coloured bands
  24. 24.True or false: an LED blows if current is high. (a) False (b) True
  25. 25.📏 Which unit measures current? (a) volt (V) (b) ohm (Ω) (c) ampere (A) (d) watt (W)
  26. 26.🧮 A 1.4 V battery is joined to 4 Ω and 3 Ω resistors in series. What current flows (in amperes)? =
  27. 27.🧩 Which component boosts a small signal? (a) buzzer (b) diode (c) thermistor (d) transistor
  28. 28.🔺 A current of 50 mA flows when 7.5 V is joined across a resistor. What is its resistance (in ohms)?
  29. 29.💡 On an LED, is the round-side leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
  30. 30.🧾 One “unit” on an electricity bill is … (a) 1 ampere (b) 1 kilowatt-hour (kWh) (c) 1 watt (d) 1 volt
  31. 31.🔺 A current of 0.5 A flows when 3 V is joined across a resistor. What is its resistance (in ohms)?
  32. 32.🌈 In the resistor colour code, which number does violet stand for?
  33. 33.🔺 A 4 V supply is joined across a 20 Ω resistor. What current flows (in amperes)? =
  34. 34.⚡ Which formula gives electric power? (a) P = V + I (b) P = I ÷ V (c) P = V × I (d) P = V ÷ I
  35. 35.📏 In the water-pipe picture of a circuit, resistance is like … (a) the water pressure (b) a bigger tank (c) a narrow pipe (d) the flow of water
  36. 36.🌈 Which band is read first on a resistor? (a) any band (b) the gold band (c) the one nearest an end (d) the widest gap
  37. 37.⚡ A home appliance on the 230 V mains takes 0.5 A. What is its power (in watts)?
  38. 38.🧮 A 0.9 V battery is joined to 3 Ω and 6 Ω resistors in series. What current flows (in amperes)? =
  39. 39.🔺 A current of 10 mA flows through a 220 Ω resistor. What is the voltage across it (in volts)? =
  40. 40.🔺 A current of 2 A flows through an 8 Ω resistor. What is the voltage across it (in volts)? =

Answer key

  1. 705
  2. less than either one
  3. V = I × R
  4. leave the TV on standby
  5. motor
  6. 20
  7. 287
  8. bigger
  9. R = V ÷ I
  10. 345
  11. 3
  12. light-emitting diode
  13. resistor
  14. 15
  15. 0.6
  16. boosts a small signal
  17. 5 %
  18. 0.3
  19. False
  20. 72
  21. 50
  22. yellow-violet-orange
  23. lets current go one way
  24. False
  25. ampere (A)
  26. 0.2
  27. transistor
  28. 150
  29. anode (+)
  30. 1 kilowatt-hour (kWh)
  31. 6
  32. 7
  33. 0.2
  34. P = V × I
  35. a narrow pipe
  36. the one nearest an end
  37. 115
  38. 0.1
  39. 2.2
  40. 16

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