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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 201 · 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 red LED (it uses 2 V) is joined with a 200 Ω resistor to a 4 V supply. What current flows (in mA)?
  2. 2.🌈 A gold fourth band on a resistor means the value may be off by … (a) 5 % (b) 50 % (c) 0 % (d) 25 %
  3. 3.True or false: on an LED, the round-side leg is the anode (+). (a) False (b) True
  4. 4.⚡ Power tells us … (a) the colour of light (b) the length of a wire (c) energy used each second (d) the size of a cell
  5. 5.True or false: voltage is measured in ohms (Ω). (a) False (b) True
  6. 6.🔺 A current of 10 mA flows through a 500 Ω resistor. What is the voltage across it (in volts)? =
  7. 7.🔺 A current of 25 mA flows through a 220 Ω resistor. What is the voltage across it (in volts)? =
  8. 8.🔺 A current of 2.5 A flows through a 5 Ω resistor. What is the voltage across it (in volts)? =
  9. 9.🧩 Which part changes electrical energy into movement? (a) an LED (b) a fuse (c) a resistor (d) a motor
  10. 10.🔺 In the V-I-R triangle, how do we find R? (a) R = V + I (b) R = V × I (c) R = V ÷ I (d) R = I ÷ V
  11. 11.🧮 Resistors of 50 Ω, 47 Ω and 47 Ω are joined in series. What is the total resistance (in ohms)?
  12. 12.⚡ A device works on 3 V and takes 1.5 A. What is its power (in watts)? =
  13. 13.📏 How many kilo-ohms (kΩ) is 6200 Ω? =
  14. 14.🧩 Which part changes electrical energy into sound? (a) a resistor (b) a capacitor (c) a buzzer (d) a diode
  15. 15.🔺 A current of 3 A flows through a 20 Ω resistor. What is the voltage across it (in volts)? =
  16. 16.⚡ A device works on 5 V and takes 0.2 A. What is its power (in watts)? =
  17. 17.🔺 A 2.4 V supply is joined across a 12 Ω resistor. What current flows (in amperes)? =
  18. 18.🌈 A resistor has the colour bands green, grey, orange. What is its value in kilo-ohms (kΩ)? =
  19. 19.What does an LED do? (a) blows if current is high (b) glows using little power (c) lets current go one way (d) turns a fan or wheels
  20. 20.🧮 Resistors of 10 Ω, 10 Ω, 330 Ω and 10 Ω are joined in series. What is the total resistance (in ohms)?
  21. 21.Which of these wastes electricity? (a) set the AC to 24 °C (b) iron one shirt at a time (c) use LED lamps (d) close the fridge quickly
  22. 22.💡 A red LED uses 2 V and should get 10 mA. It runs from a 5 V supply. What resistor (in ohms) is needed in series?
  23. 23.🌈 A resistor has the colour bands white, red, brown. What is its value (in ohms)?
  24. 24.🧮 Two equal 200 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  25. 25.🔺 A 5 V supply is joined across a 100 Ω resistor. What current flows (in milliamperes, mA)?
  26. 26.🧮 Adding another resistor in series makes the total resistance … (a) smaller (b) bigger (c) stay the same (d) zero
  27. 27.🔺 A current of 2 A flows through a 15 Ω resistor. What is the voltage across it (in volts)? =
  28. 28.True or false: the voltmeter is joined in series. (a) True (b) False
  29. 29.📏 How many watts (W) is 1.1 kW?
  30. 30.🧮 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
  31. 31.🔺 A 3 V supply is joined across a 150 Ω resistor. What current flows (in milliamperes, mA)?
  32. 32.📏 How many kilo-ohms (kΩ) is 9500 Ω? =
  33. 33.True or false: voltage is measured in volts (V). (a) False (b) True
  34. 34.🔺 A 25 V supply is joined across a 10 Ω resistor. What current flows (in amperes)? =
  35. 35.True or false: a capacitor stores a little charge. (a) True (b) False
  36. 36.⚡ A home appliance on the 230 V mains takes 4 A. What is its power (in watts)?
  37. 37.📏 How many ohms make 1 kilo-ohm (kΩ)? (a) 1024 (b) 1000 (c) 100 (d) 10
  38. 38.💡 Does it save or waste electricity to use daylight to read? (a) wastes electricity (b) saves electricity
  39. 39.🧩 Which component makes a beeping sound? (a) transistor (b) buzzer (c) LED (d) fuse
  40. 40.🧩 Which component lets current go one way? (a) thermistor (b) diode (c) LDR (d) transistor

Answer key

  1. 10
  2. 5 %
  3. True
  4. energy used each second
  5. False
  6. 5
  7. 5.5
  8. 12.5
  9. a motor
  10. R = V ÷ I
  11. 144
  12. 4.5
  13. 6.2
  14. a buzzer
  15. 60
  16. 1
  17. 0.2
  18. 58
  19. glows using little power
  20. 360
  21. iron one shirt at a time
  22. 300
  23. 920
  24. 100
  25. 50
  26. bigger
  27. 30
  28. False
  29. 1100
  30. less than either one
  31. 20
  32. 9.5
  33. True
  34. 2.5
  35. True
  36. 920
  37. 1000
  38. saves electricity
  39. buzzer
  40. diode

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