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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 40 · 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.🔺 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
  2. 2.🧮 Two resistors in parallel give a total that is … (a) less than either one (b) more than either one (c) their sum (d) always zero
  3. 3.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 310 Ω resistor? (a) orange-brown-red (b) orange-brown-brown (c) brown-orange-brown (d) orange-brown-black
  4. 4.💡 An LED is joined to a 3 V battery through a 470 Ω resistor; the leg next to the flat edge of its rim goes to the − side. What happens? (a) may burn out (b) lights up (c) does not light
  5. 5.True or false: a motor turns a fan or wheels. (a) True (b) False
  6. 6.True or false: to unplug idle chargers wastes electricity. (a) False (b) True
  7. 7.🔍 Which is the odd one out? (a) leave fridge door open (b) switch off empty rooms (c) iron one shirt at a time (d) use old filament bulbs
  8. 8.🔺 A 1 V supply is joined across a 2 Ω resistor. What current flows (in amperes)? =
  9. 9.🧮 Two equal 20 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  10. 10.📏 How many amperes (A) is 1000 mA? =
  11. 11.🌈 A gold fourth band on a resistor means the value may be off by … (a) 50 % (b) 25 % (c) 5 % (d) 0 %
  12. 12.📏 Which unit measures the flow of charge? (a) ohm (Ω) (b) volt (V) (c) watt (W) (d) ampere (A)
  13. 13.What does a fuse do? (a) blows if current is high (b) senses how bright it is (c) smooths a wobbly supply (d) senses how hot it is
  14. 14.🔺 A 10 V supply is joined across a 10 Ω resistor. What current flows (in amperes)? =
  15. 15.🧮 A 330 Ω resistor is joined in series with two equal 470 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
  16. 16.🌈 A resistor has the colour bands red, violet, black. What is its value (in ohms)?
  17. 17.🔺 A current of 1 A flows when 4 V is joined across a resistor. What is its resistance (in ohms)?
  18. 18.📏 How many kilowatts (kW) is 1250 W? =
  19. 19.True or false: a buzzer glows using little power. (a) True (b) False
  20. 20.🔺 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
  21. 21.True or false: an LDR stores a little charge. (a) True (b) False
  22. 22.⚡ A 7.5 W device works on 5 V. What current does it take (in amperes)? =
  23. 23.🔺 A current of 0.2 A flows through a 4 Ω resistor. What is the voltage across it (in volts)? =
  24. 24.💡 Why does an LED need a resistor in series? (a) to store charge (b) to change its colour (c) to make it brighter (d) to limit the current
  25. 25.Which of these is measured in amperes (A)? (a) the push of a cell (b) current (c) how much a part resists (d) resistance
  26. 26.🌈 A resistor has the colour bands orange, blue, orange. What is its value (in ohms)?
  27. 27.True or false: an LDR boosts a small signal. (a) False (b) True
  28. 28.🧮 A 47 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)?
  29. 29.🔺 A 7.5 V supply is joined across a 5 Ω resistor. What current flows (in amperes)? =
  30. 30.🧩 Which component senses how hot it is? (a) fuse (b) LDR (c) thermistor (d) potentiometer
  31. 31.💡 An LED is joined to a 12 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
  32. 32.⚡ A home appliance on the 230 V mains takes 1 A. What is its power (in watts)?
  33. 33.🌈 Which band is read first on a resistor? (a) the one nearest an end (b) any band (c) the widest gap (d) the gold band
  34. 34.🧮 Resistors of 10 Ω and 33 Ω are joined in series. What is the total resistance (in ohms)?
  35. 35.📏 Voltmeter or ammeter: which one is joined across a part? (a) ammeter (b) voltmeter
  36. 36.🧩 Which component boosts a small signal? (a) transistor (b) diode (c) motor (d) LED
  37. 37.What does a diode do? (a) turns a fan or wheels (b) makes things spin (c) lets current go one way (d) blows if current is high
  38. 38.🔺 A current of 0.1 A flows through an 8 Ω resistor. What is the voltage across it (in volts)? =
  39. 39.🔺 A current of 0.1 A flows through a 20 Ω resistor. What is the voltage across it (in volts)? =
  40. 40.True or false: a motor beeps for an alarm. (a) False (b) True

Answer key

  1. R = V ÷ I
  2. less than either one
  3. orange-brown-brown
  4. lights up
  5. True
  6. False
  7. switch off empty rooms
  8. 0.5
  9. 10
  10. 1
  11. 5 %
  12. ampere (A)
  13. blows if current is high
  14. 1
  15. 565
  16. 27
  17. 4
  18. 1.25
  19. False
  20. V = I × R
  21. False
  22. 1.5
  23. 0.8
  24. to limit the current
  25. current
  26. 36000
  27. False
  28. 57
  29. 1.5
  30. thermistor
  31. may burn out
  32. 230
  33. the one nearest an end
  34. 43
  35. voltmeter
  36. transistor
  37. lets current go one way
  38. 0.8
  39. 2
  40. False

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