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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 674 · 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.📏 Which unit measures resistance? (a) volt (V) (b) ampere (A) (c) watt (W) (d) ohm (Ω)
  2. 2.True or false: the voltmeter is joined in series. (a) False (b) True
  3. 3.🔺 A 6 V supply is joined across a 12 Ω resistor. What current flows (in amperes)? =
  4. 4.🔺 A 3 V supply is joined across a 150 Ω resistor. What current flows (in milliamperes, mA)?
  5. 5.🧾 A 100 W filament bulb is swapped for a 15 W LED lamp that gives about the same light. Both would run for 10 hours. How many watt-hours (Wh) are saved?
  6. 6.🔺 A current of 0.25 A flows through a 3 Ω resistor. What is the voltage across it (in volts)? =
  7. 7.🔺 A current of 50 mA flows when 20 V is joined across a resistor. What is its resistance (in ohms)?
  8. 8.🔺 A 0.8 V supply is joined across a 4 Ω resistor. What current flows (in amperes)? =
  9. 9.What does an LED do? (a) boosts a small signal (b) smooths a wobbly supply (c) glows using little power (d) senses how hot it is
  10. 10.🧮 Two equal 100 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  11. 11.🧮 A 2.4 V battery is joined to 12 Ω and 12 Ω resistors in series. What current flows (in amperes)? =
  12. 12.Which of these wastes electricity? (a) switch off empty rooms (b) close the fridge quickly (c) leave fridge door open (d) use LED lamps
  13. 13.What does a resistor do? (a) lets current go one way (b) limits the current (c) glows using little power (d) senses how hot it is
  14. 14.🌈 In the resistor colour code, which number does grey stand for?
  15. 15.📏 How many milliamperes (mA) is 0.57 A?
  16. 16.🔺 A current of 10 mA flows through a 330 Ω resistor. What is the voltage across it (in volts)? =
  17. 17.True or false: to set the AC to 24 °C saves electricity. (a) True (b) False
  18. 18.Which of these is measured in amperes (A)? (a) the push of a cell (b) how much a part resists (c) current (d) voltage
  19. 19.🧾 A 50 W appliance runs for 10 hours. How many units (kWh) of electricity does it use? =
  20. 20.🔺 A current of 0.5 A flows through a 15 Ω resistor. What is the voltage across it (in volts)? =
  21. 21.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) becomes zero (b) gets smaller (c) stays the same (d) gets bigger
  22. 22.🔍 Which is the odd one out? (a) run fans in empty rooms (b) unplug idle chargers (c) iron one shirt at a time (d) leave the TV on standby
  23. 23.🔺 A current of 2 A flows through a 6 Ω resistor. What is the voltage across it (in volts)? =
  24. 24.🌈 A resistor has the colour bands brown, grey, orange. What is its value in kilo-ohms (kΩ)? =
  25. 25.🌈 A gold fourth band on a resistor means the value may be off by … (a) 0 % (b) 50 % (c) 5 % (d) 25 %
  26. 26.💡 Does it save or waste electricity to use LED lamps? (a) saves electricity (b) wastes electricity
  27. 27.True or false: to use old filament bulbs wastes electricity. (a) False (b) True
  28. 28.🌈 A resistor has the colour bands grey, yellow, orange. What is its value in kilo-ohms (kΩ)? =
  29. 29.🔺 A current of 3 A flows through a 2 Ω resistor. What is the voltage across it (in volts)? =
  30. 30.🔺 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
  31. 31.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 3400 Ω resistor? (a) yellow-orange-red (b) orange-yellow-orange (c) orange-yellow-brown (d) orange-yellow-red
  32. 32.💡 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) may burn out (b) does not light (c) lights up
  33. 33.📏 How many kilowatts (kW) is 4000 W? =
  34. 34.🧾 One “unit” on an electricity bill is … (a) 1 ampere (b) 1 volt (c) 1 kilowatt-hour (kWh) (d) 1 watt
  35. 35.🔺 In the V-I-R triangle, how do we find V? (a) V = R ÷ I (b) V = I × R (c) V = I ÷ R (d) V = I + R
  36. 36.🌈 A resistor has the colour bands white, brown, red. What is its value in kilo-ohms (kΩ)? =
  37. 37.⚡ Which formula gives electric power? (a) P = V ÷ I (b) P = V × I (c) P = V + I (d) P = I ÷ V
  38. 38.🧾 Which lamp gives the same light for the least power? (a) a filament bulb (b) an LED lamp (c) a candle (d) an oil lamp
  39. 39.🧾 A 75 W filament bulb is swapped for a 12 W LED lamp that gives about the same light. Both would run for 10 hours. How many watt-hours (Wh) are saved?
  40. 40.🧮 Two resistors in parallel give a total that is … (a) less than either one (b) more than either one (c) always zero (d) their sum

Answer key

  1. ohm (Ω)
  2. False
  3. 0.5
  4. 20
  5. 850
  6. 0.75
  7. 400
  8. 0.2
  9. glows using little power
  10. 50
  11. 0.1
  12. leave fridge door open
  13. limits the current
  14. 8
  15. 570
  16. 3.3
  17. True
  18. current
  19. 0.5
  20. 7.5
  21. gets smaller
  22. unplug idle chargers
  23. 12
  24. 18
  25. 5 %
  26. saves electricity
  27. True
  28. 84
  29. 6
  30. I = V ÷ R
  31. orange-yellow-red
  32. may burn out
  33. 4
  34. 1 kilowatt-hour (kWh)
  35. V = I × R
  36. 9.1
  37. P = V × I
  38. an LED lamp
  39. 630
  40. less than either one

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