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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 238 · 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 current of 0.25 A flows when 1 V is joined across a resistor. What is its resistance (in ohms)?
  2. 2.True or false: to use old filament bulbs wastes electricity. (a) False (b) True
  3. 3.🔺 A 3 V supply is joined across a 150 Ω resistor. What current flows (in milliamperes, mA)?
  4. 4.🔍 Which is the odd one out? (a) switch off empty rooms (b) set the AC to 24 °C (c) leave fridge door open (d) unplug idle chargers
  5. 5.True or false: the voltmeter measures voltage. (a) True (b) False
  6. 6.📏 How many milliamperes (mA) make 1 ampere? (a) 1000 (b) 100 (c) 60 (d) 10
  7. 7.🔺 In the V-I-R triangle, how do we find I? (a) I = V ÷ R (b) I = R ÷ V (c) I = V × R (d) I = V + R
  8. 8.🔺 A current of 25 mA flows through a 100 Ω resistor. What is the voltage across it (in volts)? =
  9. 9.📏 Voltmeter or ammeter: which one measures voltage? (a) voltmeter (b) ammeter
  10. 10.📏 How many kilo-ohms (kΩ) is 3800 Ω? =
  11. 11.📏 How many milliamperes (mA) is 2.3 A?
  12. 12.🔺 A 2 V supply is joined across a 20 Ω resistor. What current flows (in amperes)? =
  13. 13.🧮 Two equal 1000 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  14. 14.🔺 A current of 40 mA flows through a 220 Ω resistor. What is the voltage across it (in volts)? =
  15. 15.🔺 A current of 1.5 A flows through a 12 Ω resistor. What is the voltage across it (in volts)? =
  16. 16.🧮 Resistors of 330 Ω, 150 Ω, 100 Ω and 68 Ω are joined in series. What is the total resistance (in ohms)?
  17. 17.⚡ A device works on 3 V and takes 2 A. What is its power (in watts)? =
  18. 18.⚡ A device works on 6 V and takes 0.25 A. What is its power (in watts)? =
  19. 19.🔺 A current of 40 mA flows through a 400 Ω resistor. What is the voltage across it (in volts)? =
  20. 20.⚡ Which formula gives electric power? (a) P = V ÷ I (b) P = V + I (c) P = V × I (d) P = I ÷ V
  21. 21.💡 A red LED (it uses 2 V) is joined with a 150 Ω resistor to a 5 V supply. What current flows (in mA)?
  22. 22.🌈 A resistor has the colour bands blue, grey, orange. What is its value (in ohms)?
  23. 23.📏 In the water-pipe picture of a circuit, current is like … (a) the water pressure (b) the flow of water (c) the pipe colour (d) a narrow pipe
  24. 24.⚡ A device works on 6 V and takes 0.2 A. What is its power (in watts)? =
  25. 25.🔺 A current of 0.2 A flows through a 3 Ω resistor. What is the voltage across it (in volts)? =
  26. 26.🌈 Which band is read first on a resistor? (a) any band (b) the widest gap (c) the gold band (d) the one nearest an end
  27. 27.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 6200 Ω resistor? (a) blue-red-orange (b) blue-red-red (c) blue-red-brown (d) red-blue-red
  28. 28.What does an LED do? (a) limits the current (b) glows using little power (c) is a resistance knob (d) makes things spin
  29. 29.🧩 Which component stores a little charge? (a) thermistor (b) potentiometer (c) motor (d) capacitor
  30. 30.📏 How many watts (W) is 4.8 kW?
  31. 31.🔺 A current of 20 mA flows when 8 V is joined across a resistor. What is its resistance (in ohms)?
  32. 32.🔺 A 2.4 V supply is joined across a 12 Ω resistor. What current flows (in amperes)? =
  33. 33.🔺 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
  34. 34.📏 Which unit measures current? (a) volt (V) (b) watt (W) (c) ohm (Ω) (d) ampere (A)
  35. 35.🧮 A 2.8 V battery is joined to 4 Ω and 10 Ω resistors in series. What current flows (in amperes)? =
  36. 36.True or false: on an LED, the leg by the flat edge is the cathode (−). (a) True (b) False
  37. 37.📏 How many ohms (Ω) is 7 kΩ?
  38. 38.🧮 Four equal 200 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  39. 39.🔺 A current of 0.5 A flows through a 4 Ω resistor. What is the voltage across it (in volts)? =
  40. 40.⚡ A home appliance on the 230 V mains takes 2 A. What is its power (in watts)?

Answer key

  1. 4
  2. True
  3. 20
  4. leave fridge door open
  5. True
  6. 1000
  7. I = V ÷ R
  8. 2.5
  9. voltmeter
  10. 3.8
  11. 2300
  12. 0.1
  13. 500
  14. 8.8
  15. 18
  16. 648
  17. 6
  18. 1.5
  19. 16
  20. P = V × I
  21. 20
  22. 68000
  23. the flow of water
  24. 1.2
  25. 0.6
  26. the one nearest an end
  27. blue-red-red
  28. glows using little power
  29. capacitor
  30. 4800
  31. 400
  32. 0.2
  33. V = I × R
  34. ampere (A)
  35. 0.2
  36. True
  37. 7000
  38. 50
  39. 2
  40. 460

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