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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 277 · 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.💡 On an LED, is the round-side leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
  2. 2.🧮 Two resistors in parallel give a total that is … (a) always zero (b) less than either one (c) more than either one (d) their sum
  3. 3.💡 A red LED uses 2 V and should get 25 mA. It runs from a 6 V supply. What resistor (in ohms) is needed in series?
  4. 4.🌈 A resistor has the colour bands red, yellow, brown. What is its value (in ohms)?
  5. 5.⚡ A device works on 12 V and takes 0.25 A. What is its power (in watts)? =
  6. 6.True or false: a thermistor smooths a wobbly supply. (a) False (b) True
  7. 7.🧮 Resistors of 20 Ω, 470 Ω, 47 Ω and 220 Ω are joined in series. What is the total resistance (in ohms)?
  8. 8.🔺 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
  9. 9.True or false: on an LED, the leg by the flat edge is the anode (+). (a) True (b) False
  10. 10.🔺 In the V-I-R triangle, how do we find R? (a) R = I ÷ V (b) R = V + I (c) R = V ÷ I (d) R = V × I
  11. 11.🧩 Which component senses how bright it is? (a) diode (b) buzzer (c) LDR (d) capacitor
  12. 12.📏 How many milliamperes (mA) is 0.32 A?
  13. 13.🔺 A current of 40 mA flows through a 220 Ω resistor. What is the voltage across it (in volts)? =
  14. 14.📏 Voltmeter or ammeter: which one is joined across a part? (a) ammeter (b) voltmeter
  15. 15.⚡ Power tells us … (a) the colour of light (b) energy used each second (c) the size of a cell (d) the length of a wire
  16. 16.📏 Voltmeter or ammeter: which one is joined in series? (a) ammeter (b) voltmeter
  17. 17.Which of these is measured in volts (V)? (a) resistance (b) current (c) the push of a cell (d) how much a part resists
  18. 18.📏 In the water-pipe picture of a circuit, resistance is like … (a) a narrow pipe (b) a bigger tank (c) the water pressure (d) the flow of water
  19. 19.🔺 A current of 0.1 A flows through a 5 Ω resistor. What is the voltage across it (in volts)? =
  20. 20.🧾 A family uses 140 units of electricity in a month and each unit costs ₹5. What is the bill (in ₹)?
  21. 21.⚡ A home appliance on the 230 V mains takes 2 A. What is its power (in watts)?
  22. 22.🧮 A 3.6 V battery is joined to 8 Ω and 10 Ω resistors in series. What current flows (in amperes)? =
  23. 23.🌈 A resistor has the colour bands brown, brown, brown. What is its value (in ohms)?
  24. 24.🔺 A current of 1 A flows through a 10 Ω resistor. What is the voltage across it (in volts)? =
  25. 25.True or false: an LDR limits the current. (a) False (b) True
  26. 26.🧮 An 11 V battery is joined to 5 Ω and 6 Ω resistors in series. What current flows (in amperes)? =
  27. 27.🔺 A current of 10 mA flows when 2.2 V is joined across a resistor. What is its resistance (in ohms)?
  28. 28.⚡ A 9 W device works on 6 V. What current does it take (in amperes)? =
  29. 29.🧩 Which component senses how hot it is? (a) buzzer (b) fuse (c) thermistor (d) LDR
  30. 30.⚡ A 13.5 W device works on 9 V. What current does it take (in amperes)? =
  31. 31.True or false: resistance is measured in amperes (A). (a) False (b) True
  32. 32.True or false: on an LED, the shorter leg is the cathode (−). (a) False (b) True
  33. 33.⚡ A device works on 6 V and takes 1 A. What is its power (in watts)? =
  34. 34.🔺 A current of 0.25 A flows through an 8 Ω resistor. What is the voltage across it (in volts)? =
  35. 35.🔺 A 9 V supply is joined across a 6 Ω resistor. What current flows (in amperes)? =
  36. 36.True or false: on an LED, the longer leg is the anode (+). (a) True (b) False
  37. 37.🧮 Adding another resistor in series makes the total resistance … (a) zero (b) smaller (c) stay the same (d) bigger
  38. 38.Which of these saves electricity? (a) use old filament bulbs (b) leave the TV on standby (c) use LED lamps (d) leave fridge door open
  39. 39.🧾 Which lamp gives the same light for the least power? (a) a candle (b) an oil lamp (c) a filament bulb (d) an LED lamp
  40. 40.🔺 A current of 25 mA flows through a 400 Ω resistor. What is the voltage across it (in volts)? =

Answer key

  1. anode (+)
  2. less than either one
  3. 160
  4. 240
  5. 3
  6. False
  7. 757
  8. I = V ÷ R
  9. False
  10. R = V ÷ I
  11. LDR
  12. 320
  13. 8.8
  14. voltmeter
  15. energy used each second
  16. ammeter
  17. the push of a cell
  18. a narrow pipe
  19. 0.5
  20. 700
  21. 460
  22. 0.2
  23. 110
  24. 10
  25. False
  26. 1
  27. 220
  28. 1.5
  29. thermistor
  30. 1.5
  31. False
  32. True
  33. 6
  34. 2
  35. 1.5
  36. True
  37. bigger
  38. use LED lamps
  39. an LED lamp
  40. 10

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