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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 121 · 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 resistor has the colour bands white, brown, brown. What is its value (in ohms)?
  2. 2.🧮 Adding another resistor in series makes the total resistance … (a) zero (b) bigger (c) smaller (d) stay the same
  3. 3.🔺 A current of 25 mA flows through a 500 Ω resistor. What is the voltage across it (in volts)? =
  4. 4.Which of these saves electricity? (a) use LED lamps (b) use old filament bulbs (c) iron one shirt at a time (d) leave fridge door open
  5. 5.🔺 A current of 2 A flows through a 5 Ω resistor. What is the voltage across it (in volts)? =
  6. 6.🧮 A 330 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)?
  7. 7.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark an 18 Ω resistor? (a) red-grey-black (b) grey-brown-black (c) brown-grey-brown (d) brown-grey-black
  8. 8.True or false: voltage is measured in ohms (Ω). (a) False (b) True
  9. 9.🧩 Which component limits the current? (a) buzzer (b) resistor (c) motor (d) LED
  10. 10.🧩 Which component senses how hot it is? (a) LED (b) LDR (c) motor (d) thermistor
  11. 11.🔺 A current of 10 mA flows through a 500 Ω resistor. What is the voltage across it (in volts)? =
  12. 12.🔺 A 4 V supply is joined across an 8 Ω resistor. What current flows (in amperes)? =
  13. 13.🔺 A 2.5 V supply is joined across a 100 Ω resistor. What current flows (in milliamperes, mA)?
  14. 14.🧮 Two resistors in parallel give a total that is … (a) more than either one (b) less than either one (c) their sum (d) always zero
  15. 15.True or false: on an LED, the shorter leg is the anode (+). (a) True (b) False
  16. 16.🔍 Which is the odd one out? (a) unplug idle chargers (b) set the AC to 24 °C (c) use daylight to read (d) iron one shirt at a time
  17. 17.🔺 A 12.5 V supply is joined across a 500 Ω resistor. What current flows (in milliamperes, mA)?
  18. 18.🧾 One “unit” on an electricity bill is … (a) 1 watt (b) 1 kilowatt-hour (kWh) (c) 1 volt (d) 1 ampere
  19. 19.🔺 A 10 V supply is joined across a 400 Ω resistor. What current flows (in milliamperes, mA)?
  20. 20.🔺 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
  21. 21.True or false: a buzzer stores a little charge. (a) False (b) True
  22. 22.🔺 A 4 V supply is joined across a 400 Ω resistor. What current flows (in milliamperes, mA)?
  23. 23.True or false: on an LED, the shorter leg is the cathode (−). (a) False (b) True
  24. 24.True or false: a buzzer makes a beeping sound. (a) True (b) False
  25. 25.⚡ Power tells us … (a) the colour of light (b) energy used each second (c) the size of a cell (d) the length of a wire
  26. 26.What does an LDR do? (a) senses how bright it is (b) lets current go one way (c) makes things spin (d) makes a beeping sound
  27. 27.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 190 Ω resistor? (a) white-brown-brown (b) brown-white-black (c) brown-white-red (d) brown-white-brown
  28. 28.💡 On an LED, is the longer leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
  29. 29.🔺 A current of 1.5 A flows through a 2 Ω resistor. What is the voltage across it (in volts)? =
  30. 30.📏 Which unit measures power? (a) ampere (A) (b) volt (V) (c) watt (W) (d) ohm (Ω)
  31. 31.🔺 In the V-I-R triangle, how do we find I? (a) I = R ÷ V (b) I = V ÷ R (c) I = V + R (d) I = V × R
  32. 32.⚡ A device works on 6 V and takes 1.5 A. What is its power (in watts)? =
  33. 33.🧮 Two equal 330 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  34. 34.🔺 A current of 10 mA flows when 1.2 V is joined across a resistor. What is its resistance (in ohms)?
  35. 35.🔺 A current of 25 mA flows through a 400 Ω resistor. What is the voltage across it (in volts)? =
  36. 36.True or false: the ammeter measures current. (a) True (b) False
  37. 37.📏 How many kilowatts (kW) is 500 W? =
  38. 38.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) gets bigger (b) gets smaller (c) becomes zero (d) stays the same
  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.🧾 A 500 W appliance runs for 8 hours. How many units (kWh) of electricity does it use? =

Answer key

  1. 910
  2. bigger
  3. 12.5
  4. use LED lamps
  5. 10
  6. 440
  7. brown-grey-black
  8. False
  9. resistor
  10. thermistor
  11. 5
  12. 0.5
  13. 25
  14. less than either one
  15. False
  16. iron one shirt at a time
  17. 25
  18. 1 kilowatt-hour (kWh)
  19. 25
  20. R = V ÷ I
  21. False
  22. 10
  23. True
  24. True
  25. energy used each second
  26. senses how bright it is
  27. brown-white-brown
  28. anode (+)
  29. 3
  30. watt (W)
  31. I = V ÷ R
  32. 9
  33. 165
  34. 120
  35. 10
  36. True
  37. 0.5
  38. gets smaller
  39. P = V × I
  40. 4

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