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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 977 · 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.🔺 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
  2. 2.💡 A red LED (it uses 2 V) is joined with a 300 Ω resistor to a 5 V supply. What current flows (in mA)?
  3. 3.🌈 A gold fourth band on a resistor means the value may be off by … (a) 0 % (b) 50 % (c) 25 % (d) 5 %
  4. 4.🧩 A capacitor in a circuit can … (a) measure heat (b) store charge briefly (c) make light (d) spin a wheel
  5. 5.⚡ Which formula gives electric power? (a) P = V + I (b) P = I ÷ V (c) P = V × I (d) P = V ÷ I
  6. 6.🔺 An 11 V supply is joined across a 220 Ω resistor. What current flows (in milliamperes, mA)?
  7. 7.🔍 Which is the odd one out? (a) set the AC to 24 °C (b) use daylight to read (c) use LED lamps (d) iron one shirt at a time
  8. 8.Which of these saves electricity? (a) use LED lamps (b) iron one shirt at a time (c) leave the TV on standby (d) leave fridge door open
  9. 9.🔺 A current of 50 mA flows through a 400 Ω resistor. What is the voltage across it (in volts)? =
  10. 10.🔺 A 0.6 V supply is joined across a 3 Ω resistor. What current flows (in amperes)? =
  11. 11.🌈 Which band is read first on a resistor? (a) the gold band (b) the one nearest an end (c) the widest gap (d) any band
  12. 12.🔺 A current of 25 mA flows through a 120 Ω resistor. What is the voltage across it (in volts)? =
  13. 13.🔺 A current of 0.2 A flows through a 5 Ω resistor. What is the voltage across it (in volts)? =
  14. 14.True or false: resistance is measured in ohms (Ω). (a) False (b) True
  15. 15.📏 How many kilo-ohms (kΩ) is 3500 Ω? =
  16. 16.💡 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?
  17. 17.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 22 Ω resistor? (a) red-red-black (b) orange-red-black (c) red-red-brown (d) red-orange-black
  18. 18.🌈 In the resistor colour code, which number does white stand for?
  19. 19.🔺 A 4.4 V supply is joined across a 220 Ω resistor. What current flows (in milliamperes, mA)?
  20. 20.What does an LED do? (a) turns a fan or wheels (b) stores a little charge (c) makes things spin (d) glows using little power
  21. 21.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 24000 Ω resistor? (a) red-yellow-red (b) red-yellow-orange (c) red-yellow-yellow (d) yellow-red-orange
  22. 22.⚡ A device works on 24 V and takes 0.1 A. What is its power (in watts)? =
  23. 23.Which of these saves electricity? (a) use daylight to read (b) iron one shirt at a time (c) leave fridge door open (d) use old filament bulbs
  24. 24.🔺 A current of 2 A flows through a 10 Ω resistor. What is the voltage across it (in volts)? =
  25. 25.True or false: on an LED, the round-side leg is the cathode (−). (a) False (b) True
  26. 26.🔺 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
  27. 27.🔍 Which is the odd one out? (a) leave the TV on standby (b) use daylight to read (c) close the fridge quickly (d) set the AC to 24 °C
  28. 28.True or false: the flow of charge is measured in watts (W). (a) True (b) False
  29. 29.📏 In the water-pipe picture of a circuit, current is like … (a) a narrow pipe (b) the flow of water (c) the water pressure (d) the pipe colour
  30. 30.🧾 A 100 W filament bulb is swapped for a 15 W LED lamp that gives about the same light. Both would run for 6 hours. How many watt-hours (Wh) are saved?
  31. 31.⚡ A home appliance on the 230 V mains takes 2 A. What is its power (in watts)?
  32. 32.🔺 A current of 0.1 A flows when 1.2 V is joined across a resistor. What is its resistance (in ohms)?
  33. 33.🌈 A resistor has the colour bands grey, blue, yellow. What is its value in kilo-ohms (kΩ)? =
  34. 34.🌈 In the resistor colour code, which number does green stand for?
  35. 35.🔺 A current of 20 mA flows when 4.4 V is joined across a resistor. What is its resistance (in ohms)?
  36. 36.🧮 Five equal 25 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  37. 37.🔺 A current of 10 mA flows through a 120 Ω resistor. What is the voltage across it (in volts)? =
  38. 38.📏 How many milliamperes (mA) make 1 ampere? (a) 1000 (b) 100 (c) 60 (d) 10
  39. 39.🌈 A resistor has the colour bands grey, grey, orange. What is its value (in ohms)?
  40. 40.🧾 A family uses 160 units of electricity in a month and each unit costs ₹7. What is the bill (in ₹)?

Answer key

  1. R = V ÷ I
  2. 10
  3. 5 %
  4. store charge briefly
  5. P = V × I
  6. 50
  7. iron one shirt at a time
  8. use LED lamps
  9. 20
  10. 0.2
  11. the one nearest an end
  12. 3
  13. 1
  14. True
  15. 3.5
  16. 120
  17. red-red-black
  18. 9
  19. 20
  20. glows using little power
  21. red-yellow-orange
  22. 2.4
  23. use daylight to read
  24. 20
  25. False
  26. I = V ÷ R
  27. leave the TV on standby
  28. False
  29. the flow of water
  30. 510
  31. 460
  32. 12
  33. 860
  34. 5
  35. 220
  36. 5
  37. 1.2
  38. 1000
  39. 88000
  40. 1120

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