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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 700 · 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.True or false: the voltmeter measures voltage. (a) True (b) False
  2. 2.What does a potentiometer do? (a) turns a fan or wheels (b) is a resistance knob (c) blows if current is high (d) glows using little power
  3. 3.🔺 A current of 40 mA flows when 12 V is joined across a resistor. What is its resistance (in ohms)?
  4. 4.🔺 A current of 1.5 A flows through an 8 Ω resistor. What is the voltage across it (in volts)? =
  5. 5.🔺 A current of 1.5 A flows through a 3 Ω resistor. What is the voltage across it (in volts)? =
  6. 6.💡 On an LED, is the leg by the flat edge the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
  7. 7.🔍 Which is the odd one out? (a) set the AC to 24 °C (b) unplug idle chargers (c) switch off empty rooms (d) run fans in empty rooms
  8. 8.🔺 A current of 20 mA flows through a 200 Ω resistor. What is the voltage across it (in volts)? =
  9. 9.🔺 A current of 40 mA flows through a 120 Ω resistor. What is the voltage across it (in volts)? =
  10. 10.💡 An LED is joined to a 5 V battery through a 330 Ω resistor; the leg next to the flat edge of its rim goes to the − side. What happens? (a) does not light (b) may burn out (c) lights up
  11. 11.⚡ Power tells us … (a) energy used each second (b) the length of a wire (c) the colour of light (d) the size of a cell
  12. 12.🔺 A current of 20 mA flows through a 400 Ω resistor. What is the voltage across it (in volts)? =
  13. 13.💡 A red LED (it uses 2 V) is joined with a 100 Ω resistor to a 2.5 V supply. What current flows (in mA)?
  14. 14.🔺 A current of 40 mA flows through a 400 Ω resistor. What is the voltage across it (in volts)? =
  15. 15.Which of these is measured in volts (V)? (a) voltage (b) how much a part resists (c) current (d) the flow of charge
  16. 16.What does a diode do? (a) has coloured bands (b) glows using little power (c) lets current go one way (d) makes things spin
  17. 17.⚡ Which formula gives electric power? (a) P = V ÷ I (b) P = I ÷ V (c) P = V × I (d) P = V + I
  18. 18.🔺 A 50 V supply is joined across a 20 Ω resistor. What current flows (in amperes)? =
  19. 19.⚡ A device works on 9 V and takes 1.5 A. What is its power (in watts)? =
  20. 20.What does a buzzer do? (a) smooths a wobbly supply (b) glows using little power (c) makes a beeping sound (d) limits the current
  21. 21.🔺 A current of 0.1 A flows through a 20 Ω resistor. What is the voltage across it (in volts)? =
  22. 22.🔺 A current of 3 A flows through a 5 Ω resistor. What is the voltage across it (in volts)? =
  23. 23.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 710 Ω resistor? (a) violet-brown-black (b) violet-brown-brown (c) brown-violet-brown (d) violet-brown-red
  24. 24.🧮 Resistors of 68 Ω and 100 Ω are joined in series. What is the total resistance (in ohms)?
  25. 25.⚡ A 0.6 W device works on 6 V. What current does it take (in amperes)? =
  26. 26.🔺 In the V-I-R triangle, how do we find V? (a) V = I + R (b) V = R ÷ I (c) V = I ÷ R (d) V = I × R
  27. 27.🧮 Two resistors in parallel give a total that is … (a) more than either one (b) less than either one (c) their sum (d) always zero
  28. 28.True or false: the voltmeter measures current. (a) True (b) False
  29. 29.🧮 A 47 Ω resistor is joined in series with two equal 100 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
  30. 30.🌈 A resistor has the colour bands green, green, orange. What is its value in kilo-ohms (kΩ)? =
  31. 31.🔺 A current of 0.2 A flows when 0.8 V is joined across a resistor. What is its resistance (in ohms)?
  32. 32.🌈 In the resistor colour code, which number does black stand for?
  33. 33.🌈 A gold fourth band on a resistor means the value may be off by … (a) 50 % (b) 5 % (c) 0 % (d) 25 %
  34. 34.💡 What happens if an LED is put in backwards? (a) it makes a sound (b) it lights brighter (c) it does not light (d) it changes colour
  35. 35.🧩 Which part changes electrical energy into movement? (a) a resistor (b) a fuse (c) an LED (d) a motor
  36. 36.📏 How many kilowatts (kW) is 4600 W? =
  37. 37.💡 On an LED, is the longer leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
  38. 38.🧮 Adding another resistor in series makes the total resistance … (a) bigger (b) zero (c) stay the same (d) smaller
  39. 39.💡 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?
  40. 40.🧮 Two equal 50 Ω resistors are joined in parallel. What is the total resistance (in ohms)?

Answer key

  1. True
  2. is a resistance knob
  3. 300
  4. 12
  5. 4.5
  6. cathode (−)
  7. run fans in empty rooms
  8. 4
  9. 4.8
  10. lights up
  11. energy used each second
  12. 8
  13. 5
  14. 16
  15. voltage
  16. lets current go one way
  17. P = V × I
  18. 2.5
  19. 13.5
  20. makes a beeping sound
  21. 2
  22. 15
  23. violet-brown-brown
  24. 168
  25. 0.1
  26. V = I × R
  27. less than either one
  28. False
  29. 97
  30. 55
  31. 4
  32. 0
  33. 5 %
  34. it does not light
  35. a motor
  36. 4.6
  37. anode (+)
  38. bigger
  39. 450
  40. 25

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