← 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 331 · 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.🧮 Resistors of 10 Ω and 10 Ω are joined in series. What is the total resistance (in ohms)?
  2. 2.⚡ A device works on 24 V and takes 2 A. What is its power (in watts)? =
  3. 3.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark an 8000 Ω resistor? (a) white-grey-red (b) grey-black-brown (c) grey-black-orange (d) grey-black-red
  4. 4.🧮 Resistors of 20 Ω, 68 Ω, 50 Ω and 22 Ω are joined in series. What is the total resistance (in ohms)?
  5. 5.🧮 Three equal 60 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  6. 6.⚡ Which formula gives electric power? (a) P = V + I (b) P = V ÷ I (c) P = I ÷ V (d) P = V × I
  7. 7.⚡ A home appliance on the 230 V mains takes 0.5 A. What is its power (in watts)?
  8. 8.🧮 A 3.25 V battery is joined to 5 Ω and 8 Ω resistors in series. What current flows (in amperes)? =
  9. 9.🌈 In the resistor colour code, which number does grey stand for?
  10. 10.🌈 A resistor has the colour bands red, violet, orange. What is its value in kilo-ohms (kΩ)? =
  11. 11.💡 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) does not light (b) lights up (c) may burn out
  12. 12.📏 Voltmeter or ammeter: which one measures voltage? (a) voltmeter (b) ammeter
  13. 13.🔺 A current of 20 mA flows when 4.4 V is joined across a resistor. What is its resistance (in ohms)?
  14. 14.🔍 Which is the odd one out? (a) set the AC to 24 °C (b) use LED lamps (c) use old filament bulbs (d) switch off empty rooms
  15. 15.🔺 In the V-I-R triangle, how do we find V? (a) V = I ÷ R (b) V = I × R (c) V = I + R (d) V = R ÷ I
  16. 16.⚡ A home appliance on the 230 V mains takes 5 A. What is its power (in watts)?
  17. 17.⚡ Power tells us … (a) the colour of light (b) the size of a cell (c) the length of a wire (d) energy used each second
  18. 18.💡 A red LED (it uses 2 V) is joined with a 300 Ω resistor to a 3.5 V supply. What current flows (in mA)?
  19. 19.📏 How many milliamperes (mA) is 0.61 A?
  20. 20.🔺 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
  21. 21.🔺 A 9 V supply is joined across a 3 Ω resistor. What current flows (in amperes)? =
  22. 22.True or false: how much a part resists is measured in volts (V). (a) True (b) False
  23. 23.🧮 Two resistors in parallel give a total that is … (a) always zero (b) less than either one (c) their sum (d) more than either one
  24. 24.📏 Voltmeter or ammeter: which one measures current? (a) ammeter (b) voltmeter
  25. 25.🌈 A gold fourth band on a resistor means the value may be off by … (a) 25 % (b) 50 % (c) 5 % (d) 0 %
  26. 26.⚡ A home appliance on the 230 V mains takes 8 A. What is its power (in watts)?
  27. 27.🧮 Resistors of 10 Ω and 220 Ω are joined in series. What is the total resistance (in ohms)?
  28. 28.🧮 An 8 V battery is joined to 6 Ω and 2 Ω resistors in series. What current flows (in amperes)? =
  29. 29.💡 What happens if an LED is put in backwards? (a) it makes a sound (b) it changes colour (c) it does not light (d) it lights brighter
  30. 30.📏 In the water-pipe picture of a circuit, current is like … (a) a narrow pipe (b) the pipe colour (c) the water pressure (d) the flow of water
  31. 31.🔺 A 3.3 V supply is joined across a 330 Ω resistor. What current flows (in milliamperes, mA)?
  32. 32.Which of these saves electricity? (a) leave the TV on standby (b) iron one shirt at a time (c) leave fridge door open (d) use LED lamps
  33. 33.⚡ A device works on 5 V and takes 1.5 A. What is its power (in watts)? =
  34. 34.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) gets bigger (b) gets smaller (c) stays the same (d) becomes zero
  35. 35.What does a diode do? (a) lets current go one way (b) beeps for an alarm (c) stores a little charge (d) senses how bright it is
  36. 36.🧾 A 100 W filament bulb is swapped for a 15 W LED lamp that gives about the same light. Both would run for 8 hours. How many watt-hours (Wh) are saved?
  37. 37.🔺 A 24 V supply is joined across an 8 Ω resistor. What current flows (in amperes)? =
  38. 38.💡 Why does an LED need a resistor in series? (a) to change its colour (b) to make it brighter (c) to limit the current (d) to store charge
  39. 39.🧾 One “unit” on an electricity bill is … (a) 1 kilowatt-hour (kWh) (b) 1 volt (c) 1 ampere (d) 1 watt
  40. 40.⚡ A device works on 6 V and takes 1.5 A. What is its power (in watts)? =

Answer key

  1. 20
  2. 48
  3. grey-black-red
  4. 160
  5. 20
  6. P = V × I
  7. 115
  8. 0.25
  9. 8
  10. 27
  11. may burn out
  12. voltmeter
  13. 220
  14. use old filament bulbs
  15. V = I × R
  16. 1150
  17. energy used each second
  18. 5
  19. 610
  20. I = V ÷ R
  21. 3
  22. False
  23. less than either one
  24. ammeter
  25. 5 %
  26. 1840
  27. 230
  28. 1
  29. it does not light
  30. the flow of water
  31. 10
  32. use LED lamps
  33. 7.5
  34. gets smaller
  35. lets current go one way
  36. 680
  37. 3
  38. to limit the current
  39. 1 kilowatt-hour (kWh)
  40. 9

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