← 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 44 · 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.⚡ Which formula gives electric power? (a) P = I ÷ V (b) P = V ÷ I (c) P = V × I (d) P = V + I
  2. 2.🧮 Two resistors in parallel give a total that is … (a) less than either one (b) more than either one (c) their sum (d) always zero
  3. 3.What does a transistor do? (a) boosts a small signal (b) has coloured bands (c) makes things spin (d) stores a little charge
  4. 4.🔺 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
  5. 5.📏 Voltmeter or ammeter: which one measures voltage? (a) voltmeter (b) ammeter
  6. 6.🔺 An 18.8 V supply is joined across a 470 Ω resistor. What current flows (in milliamperes, mA)?
  7. 7.💡 On an LED, is the shorter leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
  8. 8.⚡ A 36 W device works on 12 V. What current does it take (in amperes)? =
  9. 9.🔺 A current of 25 mA flows through a 100 Ω resistor. What is the voltage across it (in volts)? =
  10. 10.💡 Does it save or waste electricity to use daylight to read? (a) saves electricity (b) wastes electricity
  11. 11.📏 Voltmeter or ammeter: which one is joined across a part? (a) ammeter (b) voltmeter
  12. 12.True or false: on an LED, the round-side leg is the anode (+). (a) False (b) True
  13. 13.⚡ A home appliance on the 230 V mains takes 0.5 A. What is its power (in watts)?
  14. 14.🔺 A current of 25 mA flows through a 220 Ω resistor. What is the voltage across it (in volts)? =
  15. 15.🔺 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
  16. 16.🔺 A current of 10 mA flows through a 150 Ω resistor. What is the voltage across it (in volts)? =
  17. 17.⚡ 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
  18. 18.🧮 Four equal 40 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  19. 19.💡 A blue LED uses 3 V and should get 20 mA. It runs from a 12 V supply. What resistor (in ohms) is needed in series?
  20. 20.🌈 A resistor has the colour bands yellow, yellow, red. What is its value (in ohms)?
  21. 21.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 5800 Ω resistor? (a) grey-green-red (b) green-grey-orange (c) green-grey-red (d) green-grey-brown
  22. 22.🔺 A current of 1.5 A flows through a 4 Ω resistor. What is the voltage across it (in volts)? =
  23. 23.🔺 A current of 3 A flows when 36 V is joined across a resistor. What is its resistance (in ohms)?
  24. 24.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) gets smaller (b) gets bigger (c) becomes zero (d) stays the same
  25. 25.🧾 One “unit” on an electricity bill is … (a) 1 watt (b) 1 ampere (c) 1 volt (d) 1 kilowatt-hour (kWh)
  26. 26.📏 How many watts (W) is 4.6 kW?
  27. 27.Which of these saves electricity? (a) run fans in empty rooms (b) use old filament bulbs (c) set the AC to 24 °C (d) iron one shirt at a time
  28. 28.⚡ A device works on 3 V and takes 1 A. What is its power (in watts)? =
  29. 29.🧮 Two equal 40 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  30. 30.🧩 Which component turns a fan or wheels? (a) motor (b) resistor (c) buzzer (d) transistor
  31. 31.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 9300 Ω resistor? (a) orange-white-red (b) white-orange-brown (c) white-orange-orange (d) white-orange-red
  32. 32.🌈 A gold fourth band on a resistor means the value may be off by … (a) 0 % (b) 5 % (c) 50 % (d) 25 %
  33. 33.🌈 Which band is read first on a resistor? (a) the one nearest an end (b) the gold band (c) any band (d) the widest gap
  34. 34.💡 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) does not light (b) may burn out (c) lights up
  35. 35.📏 Which unit measures current? (a) ohm (Ω) (b) ampere (A) (c) watt (W) (d) volt (V)
  36. 36.🔺 A 0.8 V supply is joined across a 4 Ω resistor. What current flows (in amperes)? =
  37. 37.🔺 A 0.6 V supply is joined across a 3 Ω resistor. What current flows (in amperes)? =
  38. 38.🧩 Which component senses how hot it is? (a) fuse (b) motor (c) resistor (d) thermistor
  39. 39.🌈 In the resistor colour code, which number does black stand for?
  40. 40.🔺 A current of 25 mA flows when 6.25 V is joined across a resistor. What is its resistance (in ohms)?

Answer key

  1. P = V × I
  2. less than either one
  3. boosts a small signal
  4. V = I × R
  5. voltmeter
  6. 40
  7. cathode (−)
  8. 3
  9. 2.5
  10. saves electricity
  11. voltmeter
  12. True
  13. 115
  14. 5.5
  15. I = V ÷ R
  16. 1.5
  17. energy used each second
  18. 10
  19. 450
  20. 4400
  21. green-grey-red
  22. 6
  23. 12
  24. gets smaller
  25. 1 kilowatt-hour (kWh)
  26. 4600
  27. set the AC to 24 °C
  28. 3
  29. 20
  30. motor
  31. white-orange-red
  32. 5 %
  33. the one nearest an end
  34. lights up
  35. ampere (A)
  36. 0.2
  37. 0.2
  38. thermistor
  39. 0
  40. 250

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