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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 749 · 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 330 Ω resistor is joined in series with two equal 1000 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
  2. 2.🌈 A resistor has the colour bands red, brown, red. What is its value in kilo-ohms (kΩ)? =
  3. 3.🔺 A current of 50 mA flows through a 250 Ω resistor. What is the voltage across it (in volts)? =
  4. 4.💡 What does LED stand for? (a) low energy device (b) light-emitting diode (c) large electric dial (d) light energy dial
  5. 5.🔺 A current of 25 mA flows through a 220 Ω resistor. What is the voltage across it (in volts)? =
  6. 6.⚡ A device works on 3 V and takes 1.5 A. What is its power (in watts)? =
  7. 7.💡 A red LED (it uses 2 V) is joined with a 300 Ω resistor to a 5 V supply. What current flows (in mA)?
  8. 8.🧮 Four equal 400 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  9. 9.💡 On an LED, is the round-side leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
  10. 10.🧮 Two resistors in parallel give a total that is … (a) their sum (b) more than either one (c) always zero (d) less than either one
  11. 11.📏 In the water-pipe picture of a circuit, resistance is like … (a) the flow of water (b) a bigger tank (c) the water pressure (d) a narrow pipe
  12. 12.🌈 A gold fourth band on a resistor means the value may be off by … (a) 50 % (b) 0 % (c) 25 % (d) 5 %
  13. 13.🔺 A current of 0.25 A flows when 1.5 V is joined across a resistor. What is its resistance (in ohms)?
  14. 14.💡 On an LED, is the longer leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
  15. 15.⚡ A device works on 5 V and takes 2 A. What is its power (in watts)? =
  16. 16.📏 In the water-pipe picture of a circuit, current is like … (a) the water pressure (b) a narrow pipe (c) the pipe colour (d) the flow of water
  17. 17.🧩 A capacitor in a circuit can … (a) store charge briefly (b) spin a wheel (c) make light (d) measure heat
  18. 18.🧮 A 22 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)?
  19. 19.🔺 A current of 3 A flows when 12 V is joined across a resistor. What is its resistance (in ohms)?
  20. 20.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 1000 Ω resistor? (a) red-brown-red (b) brown-black-brown (c) brown-black-red (d) brown-black-orange
  21. 21.🔺 A current of 40 mA flows through a 200 Ω resistor. What is the voltage across it (in volts)? =
  22. 22.🔺 In the V-I-R triangle, how do we find R? (a) R = V × I (b) R = V ÷ I (c) R = V + I (d) R = I ÷ V
  23. 23.💡 Why does an LED need a resistor in series? (a) to make it brighter (b) to store charge (c) to limit the current (d) to change its colour
  24. 24.🌈 Which band is read first on a resistor? (a) the widest gap (b) any band (c) the one nearest an end (d) the gold band
  25. 25.🔺 In the V-I-R triangle, how do we find I? (a) I = V ÷ R (b) I = V + R (c) I = V × R (d) I = R ÷ V
  26. 26.🌈 A resistor has the colour bands red, green, black. What is its value (in ohms)?
  27. 27.🧩 Which component stores a little charge? (a) buzzer (b) transistor (c) capacitor (d) fuse
  28. 28.🔺 A current of 0.25 A flows through a 15 Ω resistor. What is the voltage across it (in volts)? =
  29. 29.📏 How many kilo-ohms (kΩ) is 5400 Ω? =
  30. 30.📏 Voltmeter or ammeter: which one is joined across a part? (a) voltmeter (b) ammeter
  31. 31.🧮 Resistors of 33 Ω and 22 Ω are joined in series. What is the total resistance (in ohms)?
  32. 32.⚡ A device works on 3 V and takes 3 A. What is its power (in watts)? =
  33. 33.💡 Does it save or waste electricity to close the fridge quickly? (a) saves electricity (b) wastes electricity
  34. 34.⚡ A home appliance on the 230 V mains takes 4 A. What is its power (in watts)?
  35. 35.🔺 A 30 V supply is joined across a 10 Ω resistor. What current flows (in amperes)? =
  36. 36.⚡ A device works on 6 V and takes 0.25 A. What is its power (in watts)? =
  37. 37.🧩 Which component senses how bright it is? (a) LED (b) motor (c) LDR (d) potentiometer
  38. 38.🔺 A current of 2.5 A flows through a 4 Ω resistor. What is the voltage across it (in volts)? =
  39. 39.⚡ Which formula gives electric power? (a) P = V + I (b) P = I ÷ V (c) P = V × I (d) P = V ÷ I
  40. 40.🧾 Which lamp gives the same light for the least power? (a) a filament bulb (b) a candle (c) an oil lamp (d) an LED lamp

Answer key

  1. 830
  2. 2.1
  3. 12.5
  4. light-emitting diode
  5. 5.5
  6. 4.5
  7. 10
  8. 100
  9. anode (+)
  10. less than either one
  11. a narrow pipe
  12. 5 %
  13. 6
  14. anode (+)
  15. 10
  16. the flow of water
  17. store charge briefly
  18. 187
  19. 4
  20. brown-black-red
  21. 8
  22. R = V ÷ I
  23. to limit the current
  24. the one nearest an end
  25. I = V ÷ R
  26. 25
  27. capacitor
  28. 3.75
  29. 5.4
  30. voltmeter
  31. 55
  32. 9
  33. saves electricity
  34. 920
  35. 3
  36. 1.5
  37. LDR
  38. 10
  39. P = V × I
  40. an LED lamp

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