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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 685 · 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 25 V supply is joined across a 500 Ω resistor. What current flows (in milliamperes, mA)?
  2. 2.🔺 A current of 1.5 A flows when 30 V is joined across a resistor. What is its resistance (in ohms)?
  3. 3.🔺 A current of 2.5 A flows through a 2 Ω resistor. What is the voltage across it (in volts)? =
  4. 4.What does a buzzer do? (a) stores a little charge (b) glows using little power (c) has coloured bands (d) beeps for an alarm
  5. 5.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) gets bigger (b) gets smaller (c) becomes zero (d) stays the same
  6. 6.Which of these is measured in volts (V)? (a) energy used each second (b) power (c) the flow of charge (d) voltage
  7. 7.⚡ A home appliance on the 230 V mains takes 0.5 A. What is its power (in watts)?
  8. 8.True or false: a buzzer boosts a small signal. (a) True (b) False
  9. 9.⚡ A 1.25 W device works on 5 V. What current does it take (in amperes)? =
  10. 10.True or false: the voltmeter is joined across a part. (a) True (b) False
  11. 11.True or false: a capacitor smooths a wobbly supply. (a) False (b) True
  12. 12.🔺 In the V-I-R triangle, how do we find V? (a) V = I × R (b) V = I + R (c) V = R ÷ I (d) V = I ÷ R
  13. 13.🔺 A current of 2 A flows when 16 V is joined across a resistor. What is its resistance (in ohms)?
  14. 14.💡 An LED is joined to a 5 V battery through a 220 Ω resistor; the leg next to the flat edge of its rim goes to the + side. What happens? (a) lights up (b) may burn out (c) does not light
  15. 15.🔺 A 6 V supply is joined across a 4 Ω resistor. What current flows (in amperes)? =
  16. 16.Which of these is measured in ohms (Ω)? (a) energy used each second (b) current (c) how much a part resists (d) power
  17. 17.⚡ A 0.75 W device works on 3 V. What current does it take (in amperes)? =
  18. 18.True or false: on an LED, the longer leg is the anode (+). (a) True (b) False
  19. 19.🔺 A current of 2 A flows through a 15 Ω resistor. What is the voltage across it (in volts)? =
  20. 20.🌈 In the resistor colour code, which number does black stand for?
  21. 21.💡 On an LED, is the shorter leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
  22. 22.🌈 Which band is read first on a resistor? (a) the gold band (b) the one nearest an end (c) the widest gap (d) any band
  23. 23.🔺 A current of 1.5 A flows when 22.5 V is joined across a resistor. What is its resistance (in ohms)?
  24. 24.What does a motor do? (a) makes things spin (b) is a resistance knob (c) stores a little charge (d) has coloured bands
  25. 25.🧮 A 1.8 V battery is joined to 12 Ω and 6 Ω resistors in series. What current flows (in amperes)? =
  26. 26.🔺 A current of 40 mA flows through a 120 Ω resistor. What is the voltage across it (in volts)? =
  27. 27.💡 On an LED, is the longer leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
  28. 28.Which of these is measured in watts (W)? (a) current (b) the flow of charge (c) the push of a cell (d) energy used each second
  29. 29.🔺 A current of 10 mA flows when 3 V is joined across a resistor. What is its resistance (in ohms)?
  30. 30.🔺 A 0.8 V supply is joined across a 4 Ω resistor. What current flows (in amperes)? =
  31. 31.🧩 Which part changes electrical energy into movement? (a) a fuse (b) a motor (c) a resistor (d) an LED
  32. 32.True or false: a diode is a resistance knob. (a) True (b) False
  33. 33.🔍 Which is the odd one out? (a) switch off empty rooms (b) set the AC to 24 °C (c) use daylight to read (d) iron one shirt at a time
  34. 34.💡 Does it save or waste electricity to iron one shirt at a time? (a) wastes electricity (b) saves electricity
  35. 35.🔺 A current of 0.25 A flows through a 2 Ω resistor. What is the voltage across it (in volts)? =
  36. 36.🔺 A current of 10 mA flows through a 200 Ω resistor. What is the voltage across it (in volts)? =
  37. 37.🔺 A current of 10 mA flows through a 400 Ω resistor. What is the voltage across it (in volts)? =
  38. 38.🧮 Two resistors in parallel give a total that is … (a) more than either one (b) less than either one (c) always zero (d) their sum
  39. 39.🔺 A current of 10 mA flows when 3.3 V is joined across a resistor. What is its resistance (in ohms)?
  40. 40.🧮 A 150 Ω resistor is joined in series with two equal 20 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?

Answer key

  1. 50
  2. 20
  3. 5
  4. beeps for an alarm
  5. gets smaller
  6. voltage
  7. 115
  8. False
  9. 0.25
  10. True
  11. True
  12. V = I × R
  13. 8
  14. does not light
  15. 1.5
  16. how much a part resists
  17. 0.25
  18. True
  19. 30
  20. 0
  21. cathode (−)
  22. the one nearest an end
  23. 15
  24. makes things spin
  25. 0.1
  26. 4.8
  27. anode (+)
  28. energy used each second
  29. 300
  30. 0.2
  31. a motor
  32. False
  33. iron one shirt at a time
  34. wastes electricity
  35. 0.5
  36. 2
  37. 4
  38. less than either one
  39. 330
  40. 160

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