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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 779 · 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.🧮 Four equal 100 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  2. 2.🔺 A 6 V supply is joined across a 120 Ω resistor. What current flows (in milliamperes, mA)?
  3. 3.🧮 Resistors of 100 Ω, 50 Ω and 20 Ω are joined in series. What is the total resistance (in ohms)?
  4. 4.🧮 A 50 Ω resistor is joined in series with two equal 200 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
  5. 5.⚡ Power tells us … (a) the length of a wire (b) the colour of light (c) the size of a cell (d) energy used each second
  6. 6.💡 An LED is joined to a 5 V battery through a 330 Ω resistor; its long leg goes to the + side and its short leg to the − side. What happens? (a) may burn out (b) lights up (c) does not light
  7. 7.📏 How many amperes (A) is 1270 mA? =
  8. 8.⚡ A device works on 1.5 V and takes 0.1 A. What is its power (in watts)? =
  9. 9.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) stays the same (b) becomes zero (c) gets bigger (d) gets smaller
  10. 10.🌈 In the resistor colour code, which number does blue stand for?
  11. 11.💡 A red LED (it uses 2 V) is joined with a 200 Ω resistor to a 5 V supply. What current flows (in mA)?
  12. 12.🔺 A current of 50 mA flows through a 220 Ω resistor. What is the voltage across it (in volts)? =
  13. 13.🔺 A current of 20 mA flows when 6 V is joined across a resistor. What is its resistance (in ohms)?
  14. 14.🧮 Two equal 50 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  15. 15.True or false: voltage is measured in watts (W). (a) True (b) False
  16. 16.📏 How many ohms make 1 kilo-ohm (kΩ)? (a) 1024 (b) 100 (c) 1000 (d) 10
  17. 17.Which of these saves electricity? (a) run fans in empty rooms (b) leave the TV on standby (c) use daylight to read (d) iron one shirt at a time
  18. 18.True or false: the ammeter measures current. (a) False (b) True
  19. 19.🧩 Which part changes electrical energy into movement? (a) an LED (b) a motor (c) a resistor (d) a fuse
  20. 20.🌈 In the resistor colour code, which number does orange stand for?
  21. 21.🌈 A resistor has the colour bands green, black, black. What is its value (in ohms)?
  22. 22.🧾 Which lamp gives the same light for the least power? (a) a candle (b) an oil lamp (c) an LED lamp (d) a filament bulb
  23. 23.🧮 A 5 V battery is joined to 4 Ω and 6 Ω resistors in series. What current flows (in amperes)? =
  24. 24.🧮 Two equal 330 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  25. 25.⚡ A device works on 5 V and takes 0.2 A. What is its power (in watts)? =
  26. 26.🔺 A 12.5 V supply is joined across a 500 Ω resistor. What current flows (in milliamperes, mA)?
  27. 27.⚡ A 0.6 W device works on 3 V. What current does it take (in amperes)? =
  28. 28.🌈 A gold fourth band on a resistor means the value may be off by … (a) 0 % (b) 5 % (c) 25 % (d) 50 %
  29. 29.🔺 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
  30. 30.What does a potentiometer do? (a) is a resistance knob (b) beeps for an alarm (c) makes things spin (d) turns a fan or wheels
  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 family uses 30 units of electricity in a month and each unit costs ₹9. What is the bill (in ₹)?
  33. 33.💡 A red LED (it uses 2 V) is joined with a 200 Ω resistor to a 4 V supply. What current flows (in mA)?
  34. 34.🔺 A current of 1 A flows through a 2 Ω resistor. What is the voltage across it (in volts)? =
  35. 35.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 30000 Ω resistor? (a) orange-black-red (b) orange-black-yellow (c) yellow-orange-orange (d) orange-black-orange
  36. 36.🔺 A current of 10 mA flows through a 220 Ω resistor. What is the voltage across it (in volts)? =
  37. 37.True or false: the voltmeter is joined in series. (a) False (b) True
  38. 38.💡 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?
  39. 39.🔺 A current of 2 A flows when 6 V is joined across a resistor. What is its resistance (in ohms)?
  40. 40.🔺 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

Answer key

  1. 25
  2. 50
  3. 170
  4. 150
  5. energy used each second
  6. lights up
  7. 1.27
  8. 0.15
  9. gets smaller
  10. 6
  11. 15
  12. 11
  13. 300
  14. 25
  15. False
  16. 1000
  17. use daylight to read
  18. True
  19. a motor
  20. 3
  21. 50
  22. an LED lamp
  23. 0.5
  24. 165
  25. 1
  26. 25
  27. 0.2
  28. 5 %
  29. V = I × R
  30. is a resistance knob
  31. 4
  32. 270
  33. 10
  34. 2
  35. orange-black-orange
  36. 2.2
  37. False
  38. 300
  39. 3
  40. R = V ÷ I

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