← 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 186 · 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.💡 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?
  2. 2.⚡ A home appliance on the 230 V mains takes 4 A. What is its power (in watts)?
  3. 3.🔍 Which is the odd one out? (a) use LED lamps (b) leave fridge door open (c) leave the TV on standby (d) iron one shirt at a time
  4. 4.💡 Why does an LED need a resistor in series? (a) to store charge (b) to make it brighter (c) to limit the current (d) to change its colour
  5. 5.🔺 A current of 2.5 A flows through a 20 Ω resistor. What is the voltage across it (in volts)? =
  6. 6.⚡ A device works on 6 V and takes 0.5 A. What is its power (in watts)? =
  7. 7.🌈 A resistor has the colour bands grey, black, brown. What is its value (in ohms)?
  8. 8.🧮 Resistors of 330 Ω, 330 Ω, 100 Ω and 47 Ω are joined in series. What is the total resistance (in ohms)?
  9. 9.🧮 Two resistors in parallel give a total that is … (a) their sum (b) more than either one (c) always zero (d) less than either one
  10. 10.What does a potentiometer do? (a) lets current go one way (b) is a resistance knob (c) beeps for an alarm (d) stores a little charge
  11. 11.📏 How many ohms (Ω) is 2.2 kΩ?
  12. 12.💡 On an LED, is the leg by the flat edge the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
  13. 13.True or false: the push of a cell is measured in volts (V). (a) False (b) True
  14. 14.True or false: to unplug idle chargers saves electricity. (a) False (b) True
  15. 15.🔺 A current of 50 mA flows through a 220 Ω resistor. What is the voltage across it (in volts)? =
  16. 16.📏 How many amperes (A) is 2300 mA? =
  17. 17.🧾 One “unit” on an electricity bill is … (a) 1 kilowatt-hour (kWh) (b) 1 ampere (c) 1 volt (d) 1 watt
  18. 18.🔺 A current of 0.1 A flows through a 4 Ω resistor. What is the voltage across it (in volts)? =
  19. 19.What does an LED do? (a) limits the current (b) blows if current is high (c) glows using little power (d) senses how bright it is
  20. 20.🧮 Resistors of 20 Ω and 68 Ω are joined in series. What is the total resistance (in ohms)?
  21. 21.🌈 A gold fourth band on a resistor means the value may be off by … (a) 25 % (b) 0 % (c) 50 % (d) 5 %
  22. 22.🔺 A current of 0.2 A flows through a 6 Ω resistor. What is the voltage across it (in volts)? =
  23. 23.🌈 In the resistor colour code, which number does grey stand for?
  24. 24.🔺 A current of 25 mA flows through a 100 Ω resistor. What is the voltage across it (in volts)? =
  25. 25.True or false: the voltmeter measures voltage. (a) False (b) True
  26. 26.🔺 A 0.3 V supply is joined across a 3 Ω resistor. What current flows (in amperes)? =
  27. 27.🧩 Which component smooths a wobbly supply? (a) resistor (b) transistor (c) LDR (d) capacitor
  28. 28.True or false: a motor smooths a wobbly supply. (a) True (b) False
  29. 29.🔺 An 8 V supply is joined across an 8 Ω resistor. What current flows (in amperes)? =
  30. 30.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 13 Ω resistor? (a) brown-orange-black (b) red-orange-black (c) brown-orange-brown (d) orange-brown-black
  31. 31.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) becomes zero (b) stays the same (c) gets bigger (d) gets smaller
  32. 32.🧩 A capacitor in a circuit can … (a) store charge briefly (b) spin a wheel (c) measure heat (d) make light
  33. 33.True or false: on an LED, the leg by the flat edge is the anode (+). (a) False (b) True
  34. 34.📏 How many milliamperes (mA) is 2.29 A?
  35. 35.🧩 Which component senses how bright it is? (a) capacitor (b) fuse (c) motor (d) LDR
  36. 36.🧩 Which component lets current go one way? (a) diode (b) capacitor (c) resistor (d) buzzer
  37. 37.📏 How many amperes (A) is 1790 mA? =
  38. 38.🔺 A current of 1.5 A flows through a 2 Ω resistor. What is the voltage across it (in volts)? =
  39. 39.Which of these is measured in watts (W)? (a) energy used each second (b) voltage (c) how much a part resists (d) the flow of charge
  40. 40.📏 How many milliamperes (mA) is 2.92 A?

Answer key

  1. 400
  2. 920
  3. use LED lamps
  4. to limit the current
  5. 50
  6. 3
  7. 800
  8. 807
  9. less than either one
  10. is a resistance knob
  11. 2200
  12. cathode (−)
  13. True
  14. True
  15. 11
  16. 2.3
  17. 1 kilowatt-hour (kWh)
  18. 0.4
  19. glows using little power
  20. 88
  21. 5 %
  22. 1.2
  23. 8
  24. 2.5
  25. True
  26. 0.1
  27. capacitor
  28. False
  29. 1
  30. brown-orange-black
  31. gets smaller
  32. store charge briefly
  33. False
  34. 2290
  35. LDR
  36. diode
  37. 1.79
  38. 3
  39. energy used each second
  40. 2920

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