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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 253 · 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 grey, blue, orange. What is its value in kilo-ohms (kΩ)? =
  2. 2.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 7600 Ω resistor? (a) violet-blue-red (b) blue-violet-red (c) violet-blue-orange (d) violet-blue-brown
  3. 3.💡 An LED is joined to a 5 V battery through a 1000 Ω resistor; its long leg goes to the − side and its short leg to the + side. What happens? (a) may burn out (b) does not light (c) lights up
  4. 4.🧮 Resistors of 100 Ω, 150 Ω, 22 Ω and 47 Ω are joined in series. What is the total resistance (in ohms)?
  5. 5.🧩 Which component makes a beeping sound? (a) buzzer (b) resistor (c) LED (d) diode
  6. 6.🧾 One “unit” on an electricity bill is … (a) 1 watt (b) 1 kilowatt-hour (kWh) (c) 1 volt (d) 1 ampere
  7. 7.💡 What does LED stand for? (a) low energy device (b) light energy dial (c) light-emitting diode (d) large electric dial
  8. 8.💡 A red LED (it uses 2 V) is joined with a 300 Ω resistor to a 3.5 V supply. What current flows (in mA)?
  9. 9.📏 In the water-pipe picture of a circuit, voltage is like … (a) the tap handle (b) the water tank lid (c) the pipe colour (d) the water pressure
  10. 10.📏 Which unit measures energy used each second? (a) watt (W) (b) volt (V) (c) ohm (Ω) (d) ampere (A)
  11. 11.⚡ Power tells us … (a) energy used each second (b) the length of a wire (c) the size of a cell (d) the colour of light
  12. 12.True or false: to use daylight to read wastes electricity. (a) True (b) False
  13. 13.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) gets bigger (b) stays the same (c) becomes zero (d) gets smaller
  14. 14.⚡ A home appliance on the 230 V mains takes 5 A. What is its power (in watts)?
  15. 15.What does an LED do? (a) senses how hot it is (b) senses how bright it is (c) turns a fan or wheels (d) glows using little power
  16. 16.🔺 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
  17. 17.🔺 A current of 0.25 A flows through a 2 Ω resistor. What is the voltage across it (in volts)? =
  18. 18.🌈 A gold fourth band on a resistor means the value may be off by … (a) 50 % (b) 25 % (c) 0 % (d) 5 %
  19. 19.🔺 A current of 10 mA flows through a 120 Ω resistor. What is the voltage across it (in volts)? =
  20. 20.What does a capacitor do? (a) makes a beeping sound (b) smooths a wobbly supply (c) senses how hot it is (d) makes things spin
  21. 21.📏 How many kilowatts (kW) is 3700 W? =
  22. 22.🔺 A current of 2 A flows through a 6 Ω resistor. What is the voltage across it (in volts)? =
  23. 23.🔺 A current of 1.5 A flows through a 12 Ω resistor. What is the voltage across it (in volts)? =
  24. 24.🔺 A 0.75 V supply is joined across a 3 Ω resistor. What current flows (in amperes)? =
  25. 25.💡 On an LED, is the shorter leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
  26. 26.🧮 A 1 V battery is joined to 2 Ω and 8 Ω resistors in series. What current flows (in amperes)? =
  27. 27.True or false: on an LED, the leg by the flat edge is the cathode (−). (a) True (b) False
  28. 28.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 19 Ω resistor? (a) brown-white-brown (b) white-brown-black (c) red-white-black (d) brown-white-black
  29. 29.🔺 A current of 50 mA flows when 10 V is joined across a resistor. What is its resistance (in ohms)?
  30. 30.💡 A blue LED uses 3 V and should get 10 mA. It runs from a 5 V supply. What resistor (in ohms) is needed in series?
  31. 31.Which of these is measured in volts (V)? (a) power (b) energy used each second (c) current (d) the push of a cell
  32. 32.True or false: a buzzer is a resistance knob. (a) True (b) False
  33. 33.🧾 A 60 W filament bulb is swapped for a 9 W LED lamp that gives about the same light. Both would run for 4 hours. How many watt-hours (Wh) are saved?
  34. 34.True or false: the voltmeter is joined in series. (a) False (b) True
  35. 35.🧾 A 50 W appliance runs for 4 hours. How many units (kWh) of electricity does it use? =
  36. 36.🔺 A current of 25 mA flows through a 330 Ω resistor. What is the voltage across it (in volts)? =
  37. 37.🔺 In the V-I-R triangle, how do we find V? (a) V = I + R (b) V = R ÷ I (c) V = I × R (d) V = I ÷ R
  38. 38.⚡ A device works on 24 V and takes 1 A. What is its power (in watts)? =
  39. 39.🌈 In the resistor colour code, which number does brown stand for?
  40. 40.💡 What happens if an LED is put in backwards? (a) it makes a sound (b) it changes colour (c) it does not light (d) it lights brighter

Answer key

  1. 86
  2. violet-blue-red
  3. does not light
  4. 319
  5. buzzer
  6. 1 kilowatt-hour (kWh)
  7. light-emitting diode
  8. 5
  9. the water pressure
  10. watt (W)
  11. energy used each second
  12. False
  13. gets smaller
  14. 1150
  15. glows using little power
  16. R = V ÷ I
  17. 0.5
  18. 5 %
  19. 1.2
  20. smooths a wobbly supply
  21. 3.7
  22. 12
  23. 18
  24. 0.25
  25. cathode (−)
  26. 0.1
  27. True
  28. brown-white-black
  29. 200
  30. 200
  31. the push of a cell
  32. False
  33. 204
  34. False
  35. 0.2
  36. 8.25
  37. V = I × R
  38. 24
  39. 1
  40. it does not light

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