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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 360 · 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 1 A flows through a 20 Ω resistor. What is the voltage across it (in volts)? =
  2. 2.🧩 Which part changes electrical energy into sound? (a) a resistor (b) a buzzer (c) a diode (d) a capacitor
  3. 3.True or false: on an LED, the leg by the flat edge is the cathode (−). (a) False (b) True
  4. 4.💡 What happens if an LED is put in backwards? (a) it changes colour (b) it does not light (c) it makes a sound (d) it lights brighter
  5. 5.⚡ Power tells us … (a) the colour of light (b) the length of a wire (c) the size of a cell (d) energy used each second
  6. 6.🔺 A current of 2 A flows through an 8 Ω resistor. What is the voltage across it (in volts)? =
  7. 7.📏 Voltmeter or ammeter: which one is joined in series? (a) voltmeter (b) ammeter
  8. 8.🔺 A 5.5 V supply is joined across a 220 Ω resistor. What current flows (in milliamperes, mA)?
  9. 9.🧮 Two equal 40 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  10. 10.🧮 A 22 Ω resistor is joined in series with two equal 1000 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
  11. 11.What does an LDR do? (a) senses how hot it is (b) has coloured bands (c) senses how bright it is (d) smooths a wobbly supply
  12. 12.⚡ A device works on 9 V and takes 0.2 A. What is its power (in watts)? =
  13. 13.🧮 Two resistors in parallel give a total that is … (a) always zero (b) less than either one (c) their sum (d) more than either one
  14. 14.📏 How many kilo-ohms (kΩ) is 4000 Ω? =
  15. 15.🔺 A 4 V supply is joined across a 2 Ω resistor. What current flows (in amperes)? =
  16. 16.True or false: to run fans in empty rooms saves electricity. (a) True (b) False
  17. 17.🌈 A resistor has the colour bands blue, yellow, orange. What is its value in kilo-ohms (kΩ)? =
  18. 18.True or false: a capacitor stores a little charge. (a) False (b) True
  19. 19.💡 On an LED, is the round-side leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
  20. 20.🔺 A current of 10 mA flows through a 470 Ω resistor. What is the voltage across it (in volts)? =
  21. 21.Which of these is measured in ohms (Ω)? (a) voltage (b) power (c) energy used each second (d) resistance
  22. 22.⚡ A 0.3 W device works on 3 V. What current does it take (in amperes)? =
  23. 23.🧩 Which component lets current go one way? (a) diode (b) resistor (c) thermistor (d) fuse
  24. 24.🧾 A family uses 90 units of electricity in a month and each unit costs ₹5. What is the bill (in ₹)?
  25. 25.🔺 A current of 0.25 A flows when 0.5 V is joined across a resistor. What is its resistance (in ohms)?
  26. 26.🧮 Resistors of 100 Ω, 220 Ω and 33 Ω are joined in series. What is the total resistance (in ohms)?
  27. 27.🔍 Which is the odd one out? (a) use LED lamps (b) set the AC to 24 °C (c) use old filament bulbs (d) close the fridge quickly
  28. 28.🔺 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
  29. 29.⚡ Which formula gives electric power? (a) P = V + I (b) P = I ÷ V (c) P = V ÷ I (d) P = V × I
  30. 30.🔺 An 18 V supply is joined across a 12 Ω resistor. What current flows (in amperes)? =
  31. 31.💡 A red LED (it uses 2 V) is joined with a 200 Ω resistor to a 6 V supply. What current flows (in mA)?
  32. 32.What does a fuse do? (a) lets current go one way (b) blows if current is high (c) beeps for an alarm (d) turns a fan or wheels
  33. 33.🧮 Resistors of 33 Ω, 10 Ω and 33 Ω are joined in series. What is the total resistance (in ohms)?
  34. 34.🔺 A current of 1.5 A flows when 15 V is joined across a resistor. What is its resistance (in ohms)?
  35. 35.True or false: on an LED, the round-side leg is the anode (+). (a) True (b) False
  36. 36.⚡ A device works on 3 V and takes 0.1 A. What is its power (in watts)? =
  37. 37.Which of these saves electricity? (a) leave the TV on standby (b) leave fridge door open (c) switch off empty rooms (d) run fans in empty rooms
  38. 38.True or false: the ammeter measures voltage. (a) True (b) False
  39. 39.True or false: current is measured in amperes (A). (a) False (b) True
  40. 40.🔺 A 6 V supply is joined across a 3 Ω resistor. What current flows (in amperes)? =

Answer key

  1. 20
  2. a buzzer
  3. True
  4. it does not light
  5. energy used each second
  6. 16
  7. ammeter
  8. 25
  9. 20
  10. 522
  11. senses how bright it is
  12. 1.8
  13. less than either one
  14. 4
  15. 2
  16. False
  17. 64
  18. True
  19. anode (+)
  20. 4.7
  21. resistance
  22. 0.1
  23. diode
  24. 450
  25. 2
  26. 353
  27. use old filament bulbs
  28. V = I × R
  29. P = V × I
  30. 1.5
  31. 20
  32. blows if current is high
  33. 76
  34. 10
  35. True
  36. 0.3
  37. switch off empty rooms
  38. False
  39. True
  40. 2

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