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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 239 · 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.

NameDateTime takenScore ___ / 40
  1. 1.🔍 Which is the odd one out? (a) leave the TV on standby (b) set the AC to 24 °C (c) leave fridge door open (d) run fans in empty rooms
  2. 2.🧩 A capacitor in a circuit can … (a) measure heat (b) make light (c) spin a wheel (d) store charge briefly
  3. 3.🧩 Which component has coloured bands? (a) resistor (b) fuse (c) buzzer (d) LDR
  4. 4.💡 An LED is joined to a 6 V battery with no resistor; the leg next to the flat edge of its rim goes to the − side. What happens? (a) lights up (b) may burn out (c) does not light
  5. 5.What does a fuse do? (a) boosts a small signal (b) smooths a wobbly supply (c) glows using little power (d) blows if current is high
  6. 6.Which of these is measured in watts (W)? (a) the push of a cell (b) how much a part resists (c) current (d) power
  7. 7.🔺 A current of 25 mA flows through a 100 Ω resistor. What is the voltage across it (in volts)? =
  8. 8.True or false: an LDR beeps for an alarm. (a) True (b) False
  9. 9.🧮 A 3.5 V battery is joined to 2 Ω and 5 Ω resistors in series. What current flows (in amperes)? =
  10. 10.🧮 A 68 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)?
  11. 11.🔺 A 12.5 V supply is joined across a 500 Ω resistor. What current flows (in milliamperes, mA)?
  12. 12.True or false: to use daylight to read saves electricity. (a) True (b) False
  13. 13.🔺 A current of 40 mA flows through a 400 Ω resistor. What is the voltage across it (in volts)? =
  14. 14.🔺 A current of 2.5 A flows through a 12 Ω resistor. What is the voltage across it (in volts)? =
  15. 15.🔺 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
  16. 16.⚡ A home appliance on the 230 V mains takes 1.5 A. What is its power (in watts)?
  17. 17.🧩 Which component stores a little charge? (a) capacitor (b) LED (c) buzzer (d) thermistor
  18. 18.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) stays the same (b) gets bigger (c) gets smaller (d) becomes zero
  19. 19.🔺 A 3 V supply is joined across a 300 Ω resistor. What current flows (in milliamperes, mA)?
  20. 20.🧾 One “unit” on an electricity bill is … (a) 1 volt (b) 1 kilowatt-hour (kWh) (c) 1 ampere (d) 1 watt
  21. 21.🔺 A current of 20 mA flows when 6 V is joined across a resistor. What is its resistance (in ohms)?
  22. 22.🧮 A 33 Ω resistor is joined in series with two equal 220 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
  23. 23.🌈 In the resistor colour code, which number does grey stand for?
  24. 24.🔺 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
  25. 25.🌈 Which band is read first on a resistor? (a) the gold band (b) any band (c) the one nearest an end (d) the widest gap
  26. 26.True or false: a diode is a resistance knob. (a) False (b) True
  27. 27.💡 What happens if an LED is put in backwards? (a) it lights brighter (b) it changes colour (c) it does not light (d) it makes a sound
  28. 28.🔺 A 1 V supply is joined across a 100 Ω resistor. What current flows (in milliamperes, mA)?
  29. 29.True or false: an LED limits the current. (a) True (b) False
  30. 30.📏 Voltmeter or ammeter: which one is joined in series? (a) ammeter (b) voltmeter
  31. 31.True or false: the ammeter is joined across a part. (a) True (b) False
  32. 32.🔺 A 3 V supply is joined across a 3 Ω resistor. What current flows (in amperes)? =
  33. 33.🔺 A 15 V supply is joined across a 15 Ω resistor. What current flows (in amperes)? =
  34. 34.🔺 A 6.6 V supply is joined across a 330 Ω resistor. What current flows (in milliamperes, mA)?
  35. 35.📏 How many ohms make 1 kilo-ohm (kΩ)? (a) 1024 (b) 100 (c) 1000 (d) 10
  36. 36.🧮 Resistors of 20 Ω, 20 Ω, 22 Ω and 68 Ω are joined in series. What is the total resistance (in ohms)?
  37. 37.💡 On an LED, is the round-side leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
  38. 38.⚡ A device works on 6 V and takes 0.1 A. What is its power (in watts)? =
  39. 39.🧩 Which component makes a beeping sound? (a) fuse (b) buzzer (c) resistor (d) capacitor
  40. 40.⚡ A 4.8 W device works on 24 V. What current does it take (in amperes)? =

Answer key

  1. set the AC to 24 °C
  2. store charge briefly
  3. resistor
  4. may burn out
  5. blows if current is high
  6. power
  7. 2.5
  8. False
  9. 0.5
  10. 78
  11. 25
  12. True
  13. 16
  14. 30
  15. V = I × R
  16. 345
  17. capacitor
  18. gets smaller
  19. 10
  20. 1 kilowatt-hour (kWh)
  21. 300
  22. 143
  23. 8
  24. R = V ÷ I
  25. the one nearest an end
  26. False
  27. it does not light
  28. 10
  29. False
  30. ammeter
  31. False
  32. 1
  33. 1
  34. 20
  35. 1000
  36. 130
  37. anode (+)
  38. 0.6
  39. buzzer
  40. 0.2

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