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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 330 · 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 I? (a) I = V ÷ R (b) I = R ÷ V (c) I = V × R (d) I = V + R
  2. 2.📏 How many watts (W) is 0.9 kW?
  3. 3.🔺 A current of 20 mA flows through a 150 Ω resistor. What is the voltage across it (in volts)? =
  4. 4.🔺 A current of 0.25 A flows when 3 V is joined across a resistor. What is its resistance (in ohms)?
  5. 5.True or false: on an LED, the longer leg is the anode (+). (a) False (b) True
  6. 6.🔺 A current of 0.2 A flows through an 8 Ω resistor. What is the voltage across it (in volts)? =
  7. 7.What does a fuse do? (a) limits the current (b) boosts a small signal (c) senses how hot it is (d) blows if current is high
  8. 8.⚡ A device works on 6 V and takes 0.5 A. What is its power (in watts)? =
  9. 9.⚡ A home appliance on the 230 V mains takes 2 A. What is its power (in watts)?
  10. 10.🔍 Which is the odd one out? (a) use LED lamps (b) switch off empty rooms (c) use daylight to read (d) leave the TV on standby
  11. 11.🔺 In the V-I-R triangle, how do we find R? (a) R = V × I (b) R = I ÷ V (c) R = V + I (d) R = V ÷ I
  12. 12.🔺 A current of 40 mA flows through a 200 Ω resistor. What is the voltage across it (in volts)? =
  13. 13.🔺 In the V-I-R triangle, how do we find V? (a) V = R ÷ I (b) V = I × R (c) V = I ÷ R (d) V = I + R
  14. 14.💡 A red LED uses 2 V and should get 10 mA. It runs from a 6 V supply. What resistor (in ohms) is needed in series?
  15. 15.🔺 A current of 10 mA flows through a 150 Ω resistor. What is the voltage across it (in volts)? =
  16. 16.⚡ Power tells us … (a) energy used each second (b) the size of a cell (c) the colour of light (d) the length of a wire
  17. 17.🔺 A 25 V supply is joined across a 10 Ω resistor. What current flows (in amperes)? =
  18. 18.📏 How many ohms make 1 kilo-ohm (kΩ)? (a) 100 (b) 10 (c) 1024 (d) 1000
  19. 19.⚡ A home appliance on the 230 V mains takes 5 A. What is its power (in watts)?
  20. 20.🌈 A resistor has the colour bands red, blue, brown. What is its value (in ohms)?
  21. 21.🧩 Which component lets current go one way? (a) capacitor (b) resistor (c) LED (d) diode
  22. 22.🧮 Resistors of 22 Ω and 100 Ω are joined in series. What is the total resistance (in ohms)?
  23. 23.What does a resistor do? (a) is a resistance knob (b) blows if current is high (c) has coloured bands (d) beeps for an alarm
  24. 24.📏 Which unit measures current? (a) ampere (A) (b) ohm (Ω) (c) volt (V) (d) watt (W)
  25. 25.Which of these saves electricity? (a) leave the TV on standby (b) leave fridge door open (c) use old filament bulbs (d) close the fridge quickly
  26. 26.🧩 Which component glows using little power? (a) transistor (b) LED (c) diode (d) capacitor
  27. 27.📏 How many ohms (Ω) is 9.7 kΩ?
  28. 28.⚡ Which formula gives electric power? (a) P = V ÷ I (b) P = V × I (c) P = V + I (d) P = I ÷ V
  29. 29.📏 How many ohms (Ω) is 3 kΩ?
  30. 30.🔺 A current of 0.1 A flows through a 20 Ω resistor. What is the voltage across it (in volts)? =
  31. 31.💡 An LED is joined to a 6 V battery with no resistor; the leg next to the flat edge of its rim goes to the − side. What happens? (a) may burn out (b) does not light (c) lights up
  32. 32.🧩 Which part changes electrical energy into sound? (a) a resistor (b) a diode (c) a buzzer (d) a capacitor
  33. 33.🔺 A current of 40 mA flows when 10 V is joined across a resistor. What is its resistance (in ohms)?
  34. 34.🧮 Two equal 50 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  35. 35.True or false: to unplug idle chargers wastes electricity. (a) True (b) False
  36. 36.🧮 Resistors of 100 Ω, 470 Ω and 220 Ω are joined in series. What is the total resistance (in ohms)?
  37. 37.⚡ A 0.3 W device works on 1.5 V. What current does it take (in amperes)? =
  38. 38.True or false: on an LED, the longer leg is the cathode (−). (a) False (b) True
  39. 39.True or false: an LDR senses how bright it is. (a) True (b) False
  40. 40.🧾 Which lamp gives the same light for the least power? (a) a filament bulb (b) a candle (c) an oil lamp (d) an LED lamp

Answer key

  1. I = V ÷ R
  2. 900
  3. 3
  4. 12
  5. True
  6. 1.6
  7. blows if current is high
  8. 3
  9. 460
  10. leave the TV on standby
  11. R = V ÷ I
  12. 8
  13. V = I × R
  14. 400
  15. 1.5
  16. energy used each second
  17. 2.5
  18. 1000
  19. 1150
  20. 260
  21. diode
  22. 122
  23. has coloured bands
  24. ampere (A)
  25. close the fridge quickly
  26. LED
  27. 9700
  28. P = V × I
  29. 3000
  30. 2
  31. may burn out
  32. a buzzer
  33. 250
  34. 25
  35. False
  36. 790
  37. 0.2
  38. False
  39. True
  40. an LED lamp

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