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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 990 · 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.📏 How many watts (W) is 3.8 kW?
  2. 2.⚡ An 18 W device works on 6 V. What current does it take (in amperes)? =
  3. 3.🌈 A resistor has the colour bands blue, yellow, black. What is its value (in ohms)?
  4. 4.📏 How many ohms (Ω) is 6.6 kΩ?
  5. 5.🔺 A 0.4 V supply is joined across a 4 Ω resistor. What current flows (in amperes)? =
  6. 6.⚡ Power tells us … (a) the length of a wire (b) energy used each second (c) the colour of light (d) the size of a cell
  7. 7.🔺 A current of 1 A flows through a 4 Ω resistor. What is the voltage across it (in volts)? =
  8. 8.⚡ A home appliance on the 230 V mains takes 0.5 A. What is its power (in watts)?
  9. 9.🧾 A family uses 200 units of electricity in a month and each unit costs ₹5. What is the bill (in ₹)?
  10. 10.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) becomes zero (b) stays the same (c) gets bigger (d) gets smaller
  11. 11.🔺 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
  12. 12.🔺 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
  13. 13.💡 Why does an LED need a resistor in series? (a) to make it brighter (b) to store charge (c) to limit the current (d) to change its colour
  14. 14.🔺 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
  15. 15.🧮 Four equal 40 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  16. 16.🔺 A current of 0.5 A flows through a 3 Ω resistor. What is the voltage across it (in volts)? =
  17. 17.🌈 A resistor has the colour bands green, red, red. What is its value in kilo-ohms (kΩ)? =
  18. 18.⚡ A device works on 5 V and takes 0.1 A. What is its power (in watts)? =
  19. 19.🧮 A 50 Ω resistor is joined in series with two equal 470 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
  20. 20.📏 Which unit measures energy used each second? (a) volt (V) (b) ampere (A) (c) watt (W) (d) ohm (Ω)
  21. 21.💡 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?
  22. 22.True or false: on an LED, the longer leg is the anode (+). (a) False (b) True
  23. 23.💡 On an LED, is the round-side leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
  24. 24.⚡ Which formula gives electric power? (a) P = V + I (b) P = V ÷ I (c) P = V × I (d) P = I ÷ V
  25. 25.🔺 A current of 10 mA flows through a 220 Ω resistor. What is the voltage across it (in volts)? =
  26. 26.True or false: a resistor limits the current. (a) False (b) True
  27. 27.📏 How many kilowatts (kW) is 150 W? =
  28. 28.🌈 In the resistor colour code, which number does blue stand for?
  29. 29.True or false: on an LED, the longer leg is the cathode (−). (a) True (b) False
  30. 30.🔺 A current of 40 mA flows when 4.8 V is joined across a resistor. What is its resistance (in ohms)?
  31. 31.🔺 A current of 1.5 A flows when 6 V is joined across a resistor. What is its resistance (in ohms)?
  32. 32.🔺 A 60 V supply is joined across a 20 Ω resistor. What current flows (in amperes)? =
  33. 33.🧮 Four equal 200 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  34. 34.True or false: to close the fridge quickly saves electricity. (a) False (b) True
  35. 35.📏 How many kilo-ohms (kΩ) is 7400 Ω? =
  36. 36.🌈 A resistor has the colour bands white, red, red. What is its value in kilo-ohms (kΩ)? =
  37. 37.💡 A red LED uses 2 V and should get 20 mA. It runs from a 5 V supply. What resistor (in ohms) is needed in series?
  38. 38.🔺 A current of 2 A flows when 10 V is joined across a resistor. What is its resistance (in ohms)?
  39. 39.📏 How many watts (W) is 0.6 kW?
  40. 40.📏 In the water-pipe picture of a circuit, current is like … (a) the pipe colour (b) a narrow pipe (c) the flow of water (d) the water pressure

Answer key

  1. 3800
  2. 3
  3. 64
  4. 6600
  5. 0.1
  6. energy used each second
  7. 4
  8. 115
  9. 1000
  10. gets smaller
  11. I = V ÷ R
  12. R = V ÷ I
  13. to limit the current
  14. V = I × R
  15. 10
  16. 1.5
  17. 5.2
  18. 0.5
  19. 285
  20. watt (W)
  21. 120
  22. True
  23. anode (+)
  24. P = V × I
  25. 2.2
  26. True
  27. 0.15
  28. 6
  29. False
  30. 120
  31. 4
  32. 3
  33. 50
  34. True
  35. 7.4
  36. 9.2
  37. 150
  38. 5
  39. 600
  40. the flow of water

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