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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 34 · 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.📏 Voltmeter or ammeter: which one is joined across a part? (a) voltmeter (b) ammeter
  2. 2.🔺 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
  3. 3.🔍 Which is the odd one out? (a) leave the TV on standby (b) use old filament bulbs (c) set the AC to 24 °C (d) run fans in empty rooms
  4. 4.💡 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?
  5. 5.⚡ A 0.5 W device works on 5 V. What current does it take (in amperes)? =
  6. 6.Which of these saves electricity? (a) leave the TV on standby (b) run fans in empty rooms (c) switch off empty rooms (d) leave fridge door open
  7. 7.🔺 A current of 0.2 A flows when 0.6 V is joined across a resistor. What is its resistance (in ohms)?
  8. 8.📏 How many ohms make 1 kilo-ohm (kΩ)? (a) 100 (b) 1000 (c) 10 (d) 1024
  9. 9.📏 Voltmeter or ammeter: which one measures voltage? (a) voltmeter (b) ammeter
  10. 10.🌈 In the resistor colour code, which number does yellow stand for?
  11. 11.⚡ Which formula gives electric power? (a) P = V ÷ I (b) P = V + I (c) P = I ÷ V (d) P = V × I
  12. 12.💡 A red LED (it uses 2 V) is joined with a 100 Ω resistor to a 3 V supply. What current flows (in mA)?
  13. 13.💡 Does it save or waste electricity to unplug idle chargers? (a) saves electricity (b) wastes electricity
  14. 14.📏 Which unit measures energy used each second? (a) ohm (Ω) (b) watt (W) (c) ampere (A) (d) volt (V)
  15. 15.🧩 Which component smooths a wobbly supply? (a) motor (b) buzzer (c) LED (d) capacitor
  16. 16.🧮 Two equal 100 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  17. 17.⚡ Power tells us … (a) energy used each second (b) the length of a wire (c) the size of a cell (d) the colour of light
  18. 18.💡 On an LED, is the round-side leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
  19. 19.📏 Which unit measures the push of a cell? (a) volt (V) (b) watt (W) (c) ohm (Ω) (d) ampere (A)
  20. 20.💡 Does it save or waste electricity to switch off empty rooms? (a) wastes electricity (b) saves electricity
  21. 21.🧮 Two equal 200 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  22. 22.⚡ A 12 W device works on 12 V. What current does it take (in amperes)? =
  23. 23.🔺 A current of 25 mA flows when 5 V is joined across a resistor. What is its resistance (in ohms)?
  24. 24.🔺 A current of 0.25 A flows through a 6 Ω resistor. What is the voltage across it (in volts)? =
  25. 25.True or false: a thermistor stores a little charge. (a) True (b) False
  26. 26.⚡ A 1 W device works on 5 V. What current does it take (in amperes)? =
  27. 27.Which of these is measured in watts (W)? (a) energy used each second (b) current (c) the flow of charge (d) resistance
  28. 28.🔺 A current of 1.5 A flows through a 3 Ω resistor. What is the voltage across it (in volts)? =
  29. 29.🔺 A 7.5 V supply is joined across a 300 Ω resistor. What current flows (in milliamperes, mA)?
  30. 30.🧮 Five equal 250 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  31. 31.🔺 A current of 1 A flows when 4 V is joined across a resistor. What is its resistance (in ohms)?
  32. 32.🧾 A family uses 100 units of electricity in a month and each unit costs ₹5. What is the bill (in ₹)?
  33. 33.True or false: the flow of charge is measured in watts (W). (a) False (b) True
  34. 34.🧩 Which component makes things spin? (a) diode (b) LDR (c) capacitor (d) motor
  35. 35.💡 A red LED uses 2 V and should get 25 mA. It runs from a 5 V supply. What resistor (in ohms) is needed in series?
  36. 36.🧩 Which component stores a little charge? (a) LDR (b) resistor (c) capacitor (d) transistor
  37. 37.🔺 A current of 0.5 A flows through a 6 Ω resistor. What is the voltage across it (in volts)? =
  38. 38.🔺 A 2.4 V supply is joined across a 120 Ω resistor. What current flows (in milliamperes, mA)?
  39. 39.🔺 A 7.5 V supply is joined across a 150 Ω resistor. What current flows (in milliamperes, mA)?
  40. 40.🧮 Two resistors in parallel give a total that is … (a) less than either one (b) their sum (c) always zero (d) more than either one

Answer key

  1. voltmeter
  2. R = V ÷ I
  3. set the AC to 24 °C
  4. 300
  5. 0.1
  6. switch off empty rooms
  7. 3
  8. 1000
  9. voltmeter
  10. 4
  11. P = V × I
  12. 10
  13. saves electricity
  14. watt (W)
  15. capacitor
  16. 50
  17. energy used each second
  18. anode (+)
  19. volt (V)
  20. saves electricity
  21. 100
  22. 1
  23. 200
  24. 1.5
  25. False
  26. 0.2
  27. energy used each second
  28. 4.5
  29. 25
  30. 50
  31. 4
  32. 500
  33. False
  34. motor
  35. 120
  36. capacitor
  37. 3
  38. 20
  39. 50
  40. less than either one

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