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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 697 · 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 home appliance on the 230 V mains takes 4 A. What is its power (in watts)?
  2. 2.🧾 A family uses 50 units of electricity in a month and each unit costs ₹9. What is the bill (in ₹)?
  3. 3.🔺 A current of 25 mA flows when 3.75 V is joined across a resistor. What is its resistance (in ohms)?
  4. 4.⚡ A home appliance on the 230 V mains takes 10 A. What is its power (in watts)?
  5. 5.🌈 A resistor has the colour bands yellow, blue, black. What is its value (in ohms)?
  6. 6.🔺 In the V-I-R triangle, how do we find V? (a) V = I × R (b) V = I + R (c) V = I ÷ R (d) V = R ÷ I
  7. 7.📏 How many watts (W) is 2.9 kW?
  8. 8.True or false: the push of a cell is measured in amperes (A). (a) False (b) True
  9. 9.🔺 In the V-I-R triangle, how do we find I? (a) I = R ÷ V (b) I = V × R (c) I = V ÷ R (d) I = V + R
  10. 10.Which of these saves electricity? (a) switch off empty rooms (b) leave fridge door open (c) leave the TV on standby (d) use old filament bulbs
  11. 11.📏 How many ohms (Ω) is 1.7 kΩ?
  12. 12.💡 On an LED, is the round-side leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
  13. 13.True or false: on an LED, the round-side leg is the cathode (−). (a) False (b) True
  14. 14.🧮 Resistors of 22 Ω and 50 Ω are joined in series. What is the total resistance (in ohms)?
  15. 15.True or false: a fuse blows if current is high. (a) False (b) True
  16. 16.⚡ A 1 W device works on 5 V. What current does it take (in amperes)? =
  17. 17.🧩 Which component limits the current? (a) potentiometer (b) capacitor (c) fuse (d) resistor
  18. 18.🔺 A current of 50 mA flows when 5 V is joined across a resistor. What is its resistance (in ohms)?
  19. 19.🔺 A current of 25 mA flows when 11.75 V is joined across a resistor. What is its resistance (in ohms)?
  20. 20.🧾 A 250 W appliance runs for 6 hours. How many units (kWh) of electricity does it use? =
  21. 21.🧮 Two resistors in parallel give a total that is … (a) more than either one (b) their sum (c) less than either one (d) always zero
  22. 22.🌈 A resistor has the colour bands blue, grey, orange. What is its value in kilo-ohms (kΩ)? =
  23. 23.🌈 A resistor has the colour bands violet, orange, orange. What is its value in kilo-ohms (kΩ)? =
  24. 24.🧩 A capacitor in a circuit can … (a) measure heat (b) store charge briefly (c) make light (d) spin a wheel
  25. 25.📏 Voltmeter or ammeter: which one measures current? (a) voltmeter (b) ammeter
  26. 26.🧮 Two equal 10 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  27. 27.🧮 Adding another resistor in series makes the total resistance … (a) bigger (b) stay the same (c) zero (d) smaller
  28. 28.⚡ Which formula gives electric power? (a) P = V ÷ I (b) P = V × I (c) P = I ÷ V (d) P = V + I
  29. 29.🔺 A current of 0.2 A flows through a 2 Ω resistor. What is the voltage across it (in volts)? =
  30. 30.🔺 A current of 50 mA flows through a 150 Ω resistor. What is the voltage across it (in volts)? =
  31. 31.📏 How many ohms (Ω) is 7.6 kΩ?
  32. 32.🔺 A current of 3 A flows through an 8 Ω resistor. What is the voltage across it (in volts)? =
  33. 33.💡 Does it save or waste electricity to use daylight to read? (a) wastes electricity (b) saves electricity
  34. 34.💡 What happens if an LED is put in backwards? (a) it changes colour (b) it lights brighter (c) it does not light (d) it makes a sound
  35. 35.⚡ Power tells us … (a) the length of a wire (b) the size of a cell (c) the colour of light (d) energy used each second
  36. 36.🌈 A gold fourth band on a resistor means the value may be off by … (a) 50 % (b) 0 % (c) 25 % (d) 5 %
  37. 37.🌈 A resistor has the colour bands blue, green, black. What is its value (in ohms)?
  38. 38.⚡ A device works on 1.5 V and takes 0.25 A. What is its power (in watts)? =
  39. 39.🔺 A current of 20 mA flows when 2 V is joined across a resistor. What is its resistance (in ohms)?
  40. 40.🔺 A current of 20 mA flows through a 200 Ω resistor. What is the voltage across it (in volts)? =

Answer key

  1. 920
  2. 450
  3. 150
  4. 2300
  5. 46
  6. V = I × R
  7. 2900
  8. False
  9. I = V ÷ R
  10. switch off empty rooms
  11. 1700
  12. anode (+)
  13. False
  14. 72
  15. True
  16. 0.2
  17. resistor
  18. 100
  19. 470
  20. 1.5
  21. less than either one
  22. 68
  23. 73
  24. store charge briefly
  25. ammeter
  26. 5
  27. bigger
  28. P = V × I
  29. 0.4
  30. 7.5
  31. 7600
  32. 24
  33. saves electricity
  34. it does not light
  35. energy used each second
  36. 5 %
  37. 65
  38. 0.375
  39. 100
  40. 4

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