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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 906 · 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.

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  1. 1.🔺 A current of 0.2 A flows through a 3 Ω resistor. What is the voltage across it (in volts)? =
  2. 2.🔺 A 1.5 V supply is joined across a 150 Ω resistor. What current flows (in milliamperes, mA)?
  3. 3.🧮 Resistors of 10 Ω and 68 Ω are joined in series. What is the total resistance (in ohms)?
  4. 4.🧮 Resistors of 150 Ω and 220 Ω are joined in series. What is the total resistance (in ohms)?
  5. 5.💡 A red LED (it uses 2 V) is joined with a 300 Ω resistor to an 8 V supply. What current flows (in mA)?
  6. 6.⚡ A home appliance on the 230 V mains takes 2 A. What is its power (in watts)?
  7. 7.🧮 Resistors of 22 Ω, 10 Ω and 150 Ω are joined in series. What is the total resistance (in ohms)?
  8. 8.💡 A red LED (it uses 2 V) is joined with a 100 Ω resistor to a 4 V supply. What current flows (in mA)?
  9. 9.🔺 A current of 0.25 A flows when 3 V is joined across a resistor. What is its resistance (in ohms)?
  10. 10.🧩 Which component is a resistance knob? (a) diode (b) LED (c) resistor (d) potentiometer
  11. 11.🌈 A gold fourth band on a resistor means the value may be off by … (a) 0 % (b) 50 % (c) 5 % (d) 25 %
  12. 12.💡 A red LED (it uses 2 V) is joined with a 200 Ω resistor to a 3 V supply. What current flows (in mA)?
  13. 13.🔺 A current of 1.5 A flows through a 4 Ω resistor. What is the voltage across it (in volts)? =
  14. 14.True or false: a capacitor senses how hot it is. (a) True (b) False
  15. 15.⚡ A home appliance on the 230 V mains takes 10 A. What is its power (in watts)?
  16. 16.🔺 A current of 10 mA flows through a 470 Ω resistor. What is the voltage across it (in volts)? =
  17. 17.🔺 A current of 50 mA flows through a 200 Ω resistor. What is the voltage across it (in volts)? =
  18. 18.🔺 An 8 V supply is joined across a 400 Ω resistor. What current flows (in milliamperes, mA)?
  19. 19.💡 What happens if an LED is put in backwards? (a) it makes a sound (b) it does not light (c) it changes colour (d) it lights brighter
  20. 20.🔺 A current of 40 mA flows when 13.2 V is joined across a resistor. What is its resistance (in ohms)?
  21. 21.🧮 Two resistors in parallel give a total that is … (a) less than either one (b) their sum (c) always zero (d) more than either one
  22. 22.🧾 One “unit” on an electricity bill is … (a) 1 watt (b) 1 volt (c) 1 ampere (d) 1 kilowatt-hour (kWh)
  23. 23.🌈 A resistor has the colour bands orange, green, orange. What is its value in kilo-ohms (kΩ)? =
  24. 24.⚡ A home appliance on the 230 V mains takes 4 A. What is its power (in watts)?
  25. 25.⚡ A device works on 3 V and takes 1.5 A. What is its power (in watts)? =
  26. 26.True or false: an LDR blows if current is high. (a) False (b) True
  27. 27.🌈 In the resistor colour code, which number does white stand for?
  28. 28.🔺 In the V-I-R triangle, how do we find I? (a) I = V + R (b) I = V × R (c) I = R ÷ V (d) I = V ÷ R
  29. 29.🔺 A current of 2.5 A flows when 30 V is joined across a resistor. What is its resistance (in ohms)?
  30. 30.🔺 A 4 V supply is joined across a 20 Ω resistor. What current flows (in amperes)? =
  31. 31.True or false: the ammeter measures voltage. (a) False (b) True
  32. 32.🔺 A current of 40 mA flows when 18.8 V is joined across a resistor. What is its resistance (in ohms)?
  33. 33.What does a thermistor do? (a) senses how hot it is (b) is a resistance knob (c) lets current go one way (d) blows if current is high
  34. 34.📏 How many ohms make 1 kilo-ohm (kΩ)? (a) 1024 (b) 10 (c) 1000 (d) 100
  35. 35.🧮 Adding another resistor in series makes the total resistance … (a) bigger (b) zero (c) smaller (d) stay the same
  36. 36.🧮 An 8 V battery is joined to 3 Ω and 5 Ω resistors in series. What current flows (in amperes)? =
  37. 37.Which of these wastes electricity? (a) use LED lamps (b) unplug idle chargers (c) leave the TV on standby (d) set the AC to 24 °C
  38. 38.🔺 A current of 1 A flows when 2 V is joined across a resistor. What is its resistance (in ohms)?
  39. 39.⚡ A 36 W device works on 12 V. What current does it take (in amperes)? =
  40. 40.🌈 A resistor has the colour bands grey, violet, red. What is its value (in ohms)?

Answer key

  1. 0.6
  2. 10
  3. 78
  4. 370
  5. 20
  6. 460
  7. 182
  8. 20
  9. 12
  10. potentiometer
  11. 5 %
  12. 5
  13. 6
  14. False
  15. 2300
  16. 4.7
  17. 10
  18. 20
  19. it does not light
  20. 330
  21. less than either one
  22. 1 kilowatt-hour (kWh)
  23. 35
  24. 920
  25. 4.5
  26. False
  27. 9
  28. I = V ÷ R
  29. 12
  30. 0.2
  31. False
  32. 470
  33. senses how hot it is
  34. 1000
  35. bigger
  36. 1
  37. leave the TV on standby
  38. 2
  39. 3
  40. 8700

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