← Part 2 test: components and Ohm’s law lesson New set →

Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 278 · 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.

NameDateTime takenScore ___ / 40
  1. 1.🧮 Two equal 200 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  2. 2.What does an LED do? (a) glows using little power (b) blows if current is high (c) smooths a wobbly supply (d) has coloured bands
  3. 3.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 78 Ω resistor? (a) grey-grey-black (b) violet-grey-black (c) grey-violet-black (d) violet-grey-brown
  4. 4.💡 A red LED uses 2 V and should get 20 mA. It runs from a 9 V supply. What resistor (in ohms) is needed in series?
  5. 5.📏 How many kilo-ohms (kΩ) is 9200 Ω? =
  6. 6.🧩 Which part changes electrical energy into sound? (a) a resistor (b) a diode (c) a buzzer (d) a capacitor
  7. 7.🌈 Which band is read first on a resistor? (a) the widest gap (b) the gold band (c) any band (d) the one nearest an end
  8. 8.⚡ Which formula gives electric power? (a) P = V + I (b) P = I ÷ V (c) P = V × I (d) P = V ÷ I
  9. 9.🧮 A 150 Ω resistor is joined in series with two equal 20 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
  10. 10.🔺 A current of 3 A flows through a 4 Ω resistor. What is the voltage across it (in volts)? =
  11. 11.💡 A red LED uses 2 V and should get 25 mA. It runs from a 12 V supply. What resistor (in ohms) is needed in series?
  12. 12.Which of these wastes electricity? (a) switch off empty rooms (b) leave fridge door open (c) use daylight to read (d) close the fridge quickly
  13. 13.🔺 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
  14. 14.🧩 Which part changes electrical energy into movement? (a) an LED (b) a fuse (c) a motor (d) a resistor
  15. 15.🧮 Two resistors in parallel give a total that is … (a) more than either one (b) always zero (c) their sum (d) less than either one
  16. 16.🔺 A current of 20 mA flows when 8 V is joined across a resistor. What is its resistance (in ohms)?
  17. 17.🔍 Which is the odd one out? (a) iron one shirt at a time (b) use old filament bulbs (c) leave the TV on standby (d) unplug idle chargers
  18. 18.🔺 A current of 25 mA flows when 3 V is joined across a resistor. What is its resistance (in ohms)?
  19. 19.💡 On an LED, is the leg by the flat edge the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
  20. 20.⚡ Power tells us … (a) energy used each second (b) the size of a cell (c) the length of a wire (d) the colour of light
  21. 21.🧮 Resistors of 330 Ω, 100 Ω, 470 Ω and 100 Ω are joined in series. What is the total resistance (in ohms)?
  22. 22.📏 In the water-pipe picture of a circuit, current is like … (a) a narrow pipe (b) the water pressure (c) the flow of water (d) the pipe colour
  23. 23.🌈 A resistor has the colour bands violet, grey, yellow. What is its value in kilo-ohms (kΩ)? =
  24. 24.🌈 A gold fourth band on a resistor means the value may be off by … (a) 50 % (b) 5 % (c) 0 % (d) 25 %
  25. 25.🔺 A current of 1.5 A flows through a 2 Ω resistor. What is the voltage across it (in volts)? =
  26. 26.🔺 A current of 40 mA flows through a 200 Ω resistor. What is the voltage across it (in volts)? =
  27. 27.True or false: to close the fridge quickly saves electricity. (a) False (b) True
  28. 28.🧾 A 100 W filament bulb is swapped for a 15 W LED lamp that gives about the same light. Both would run for 5 hours. How many watt-hours (Wh) are saved?
  29. 29.⚡ A device works on 5 V and takes 3 A. What is its power (in watts)? =
  30. 30.🌈 A resistor has the colour bands grey, white, orange. What is its value in kilo-ohms (kΩ)? =
  31. 31.📏 Which unit measures resistance? (a) ampere (A) (b) watt (W) (c) volt (V) (d) ohm (Ω)
  32. 32.🔺 A current of 10 mA flows when 2 V is joined across a resistor. What is its resistance (in ohms)?
  33. 33.🧮 Four equal 40 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  34. 34.🧮 Adding another resistor in series makes the total resistance … (a) stay the same (b) zero (c) bigger (d) smaller
  35. 35.💡 An LED is joined to a 5 V battery with no resistor; its long leg goes to the + side and its short leg to the − side. What happens? (a) does not light (b) may burn out (c) lights up
  36. 36.🔺 A current of 10 mA flows through a 120 Ω resistor. What is the voltage across it (in volts)? =
  37. 37.True or false: the ammeter is joined in series. (a) False (b) True
  38. 38.🧮 Four equal 20 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  39. 39.True or false: a thermistor senses how hot it is. (a) False (b) True
  40. 40.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) gets bigger (b) stays the same (c) gets smaller (d) becomes zero

Answer key

  1. 100
  2. glows using little power
  3. violet-grey-black
  4. 350
  5. 9.2
  6. a buzzer
  7. the one nearest an end
  8. P = V × I
  9. 160
  10. 12
  11. 400
  12. leave fridge door open
  13. I = V ÷ R
  14. a motor
  15. less than either one
  16. 400
  17. unplug idle chargers
  18. 120
  19. cathode (−)
  20. energy used each second
  21. 1000
  22. the flow of water
  23. 780
  24. 5 %
  25. 3
  26. 8
  27. True
  28. 425
  29. 15
  30. 89
  31. ohm (Ω)
  32. 200
  33. 10
  34. bigger
  35. may burn out
  36. 1.2
  37. True
  38. 5
  39. True
  40. gets smaller

Free electronics lessons, practice and worksheets at talentjr.in/electronics-for-kids