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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 339 · 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 22.5 V supply is joined across a 15 Ω resistor. What current flows (in amperes)? =
  2. 2.🔺 A current of 50 mA flows through a 470 Ω resistor. What is the voltage across it (in volts)? =
  3. 3.💡 On an LED, is the leg by the flat edge the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
  4. 4.🧮 Two equal 330 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  5. 5.📏 Which unit measures power? (a) watt (W) (b) ohm (Ω) (c) ampere (A) (d) volt (V)
  6. 6.💡 A red LED uses 2 V and should get 10 mA. It runs from a 5 V supply. What resistor (in ohms) is needed in series?
  7. 7.📏 How many kilo-ohms (kΩ) is 6800 Ω? =
  8. 8.🧩 Which component blows if current is high? (a) fuse (b) resistor (c) transistor (d) LDR
  9. 9.⚡ Which formula gives electric power? (a) P = I ÷ V (b) P = V × I (c) P = V ÷ I (d) P = V + I
  10. 10.🔺 A 5.5 V supply is joined across a 220 Ω resistor. What current flows (in milliamperes, mA)?
  11. 11.📏 In the water-pipe picture of a circuit, voltage is like … (a) the tap handle (b) the pipe colour (c) the water pressure (d) the water tank lid
  12. 12.⚡ A device works on 9 V and takes 0.5 A. What is its power (in watts)? =
  13. 13.🔺 In the V-I-R triangle, how do we find I? (a) I = V × R (b) I = V + R (c) I = V ÷ R (d) I = R ÷ V
  14. 14.⚡ A device works on 1.5 V and takes 1 A. What is its power (in watts)? =
  15. 15.💡 An LED is joined to a 5 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) lights up (c) does not light
  16. 16.🔺 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
  17. 17.🧮 A 2 V battery is joined to 4 Ω and 4 Ω resistors in series. What current flows (in amperes)? =
  18. 18.🧮 Two equal 100 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  19. 19.🔺 A current of 1 A flows through a 2 Ω resistor. What is the voltage across it (in volts)? =
  20. 20.What does a buzzer do? (a) turns a fan or wheels (b) beeps for an alarm (c) smooths a wobbly supply (d) lets current go one way
  21. 21.🧩 Which component limits the current? (a) potentiometer (b) buzzer (c) resistor (d) diode
  22. 22.🧮 Adding another resistor in series makes the total resistance … (a) zero (b) stay the same (c) smaller (d) bigger
  23. 23.🔺 A current of 50 mA flows through a 200 Ω resistor. What is the voltage across it (in volts)? =
  24. 24.True or false: a thermistor senses how hot it is. (a) True (b) False
  25. 25.🔺 In the V-I-R triangle, how do we find R? (a) R = V + I (b) R = V × I (c) R = I ÷ V (d) R = V ÷ I
  26. 26.🔺 A current of 0.1 A flows when 0.2 V is joined across a resistor. What is its resistance (in ohms)?
  27. 27.🔍 Which is the odd one out? (a) leave fridge door open (b) unplug idle chargers (c) use old filament bulbs (d) leave the TV on standby
  28. 28.💡 On an LED, is the longer leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
  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 home appliance on the 230 V mains takes 10 A. What is its power (in watts)?
  31. 31.📏 How many ohms make 1 kilo-ohm (kΩ)? (a) 100 (b) 10 (c) 1024 (d) 1000
  32. 32.⚡ Power tells us … (a) the length of a wire (b) the colour of light (c) energy used each second (d) the size of a cell
  33. 33.🔺 A current of 50 mA flows through a 500 Ω resistor. What is the voltage across it (in volts)? =
  34. 34.🔺 A current of 0.2 A flows through a 4 Ω resistor. What is the voltage across it (in volts)? =
  35. 35.True or false: on an LED, the leg by the flat edge is the cathode (−). (a) False (b) True
  36. 36.🌈 Which band is read first on a resistor? (a) any band (b) the gold band (c) the widest gap (d) the one nearest an end
  37. 37.🔺 A current of 3 A flows through a 3 Ω resistor. What is the voltage across it (in volts)? =
  38. 38.🔺 A 2.4 V supply is joined across a 12 Ω resistor. What current flows (in amperes)? =
  39. 39.Which of these wastes electricity? (a) set the AC to 24 °C (b) close the fridge quickly (c) unplug idle chargers (d) use old filament bulbs
  40. 40.🧩 A capacitor in a circuit can … (a) store charge briefly (b) measure heat (c) spin a wheel (d) make light

Answer key

  1. 1.5
  2. 23.5
  3. cathode (−)
  4. 165
  5. watt (W)
  6. 300
  7. 6.8
  8. fuse
  9. P = V × I
  10. 25
  11. the water pressure
  12. 4.5
  13. I = V ÷ R
  14. 1.5
  15. may burn out
  16. V = I × R
  17. 0.25
  18. 50
  19. 2
  20. beeps for an alarm
  21. resistor
  22. bigger
  23. 10
  24. True
  25. R = V ÷ I
  26. 2
  27. unplug idle chargers
  28. anode (+)
  29. 200
  30. 2300
  31. 1000
  32. energy used each second
  33. 25
  34. 0.8
  35. True
  36. the one nearest an end
  37. 9
  38. 0.2
  39. use old filament bulbs
  40. store charge briefly

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