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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 829 · 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.📏 Which unit measures the flow of charge? (a) volt (V) (b) ohm (Ω) (c) ampere (A) (d) watt (W)
  2. 2.⚡ Which formula gives electric power? (a) P = I ÷ V (b) P = V ÷ I (c) P = V + I (d) P = V × I
  3. 3.📏 Which unit measures power? (a) volt (V) (b) ampere (A) (c) watt (W) (d) ohm (Ω)
  4. 4.🔺 A current of 2.5 A flows when 20 V is joined across a resistor. What is its resistance (in ohms)?
  5. 5.True or false: resistance is measured in watts (W). (a) True (b) False
  6. 6.True or false: a diode lets current go one way. (a) True (b) False
  7. 7.🔺 A current of 0.1 A flows when 0.6 V is joined across a resistor. What is its resistance (in ohms)?
  8. 8.🧮 A 6 V battery is joined to 8 Ω and 4 Ω resistors in series. What current flows (in amperes)? =
  9. 9.💡 Does it save or waste electricity to set the AC to 24 °C? (a) wastes electricity (b) saves electricity
  10. 10.🧮 A 50 Ω resistor is joined in series with two equal 200 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
  11. 11.⚡ A home appliance on the 230 V mains takes 5 A. What is its power (in watts)?
  12. 12.📏 How many ohms make 1 kilo-ohm (kΩ)? (a) 100 (b) 10 (c) 1024 (d) 1000
  13. 13.🔺 A current of 40 mA flows through a 150 Ω resistor. What is the voltage across it (in volts)? =
  14. 14.📏 How many milliamperes (mA) make 1 ampere? (a) 10 (b) 1000 (c) 100 (d) 60
  15. 15.🌈 A gold fourth band on a resistor means the value may be off by … (a) 25 % (b) 5 % (c) 0 % (d) 50 %
  16. 16.True or false: on an LED, the shorter leg is the anode (+). (a) False (b) True
  17. 17.🔺 A current of 0.2 A flows when 0.6 V is joined across a resistor. What is its resistance (in ohms)?
  18. 18.💡 Why does an LED need a resistor in series? (a) to limit the current (b) to store charge (c) to make it brighter (d) to change its colour
  19. 19.💡 Does it save or waste electricity to switch off empty rooms? (a) saves electricity (b) wastes electricity
  20. 20.⚡ A device works on 1.5 V and takes 1.5 A. What is its power (in watts)? =
  21. 21.📏 How many amperes (A) is 960 mA? =
  22. 22.🌈 A resistor has the colour bands brown, violet, brown. What is its value (in ohms)?
  23. 23.💡 An LED is joined to a 3 V battery through a 470 Ω resistor; the leg next to the flat edge of its rim goes to the − side. What happens? (a) may burn out (b) does not light (c) lights up
  24. 24.🔺 In the V-I-R triangle, how do we find R? (a) R = V × I (b) R = V + I (c) R = I ÷ V (d) R = V ÷ I
  25. 25.Which of these is measured in ohms (Ω)? (a) energy used each second (b) how much a part resists (c) power (d) the push of a cell
  26. 26.🌈 A resistor has the colour bands violet, red, orange. What is its value (in ohms)?
  27. 27.🔺 A 1 V supply is joined across a 100 Ω resistor. What current flows (in milliamperes, mA)?
  28. 28.True or false: an LDR boosts a small signal. (a) True (b) False
  29. 29.📏 Voltmeter or ammeter: which one measures current? (a) voltmeter (b) ammeter
  30. 30.🧮 Two equal 330 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  31. 31.🔺 A current of 2.5 A flows when 25 V is joined across a resistor. What is its resistance (in ohms)?
  32. 32.🔺 A 6.25 V supply is joined across a 250 Ω resistor. What current flows (in milliamperes, mA)?
  33. 33.⚡ A home appliance on the 230 V mains takes 10 A. What is its power (in watts)?
  34. 34.⚡ A device works on 9 V and takes 0.1 A. What is its power (in watts)? =
  35. 35.🔺 A current of 20 mA flows through a 150 Ω resistor. What is the voltage across it (in volts)? =
  36. 36.True or false: a capacitor limits the current. (a) False (b) True
  37. 37.True or false: how much a part resists is measured in amperes (A). (a) False (b) True
  38. 38.What does an LED do? (a) makes a beeping sound (b) beeps for an alarm (c) glows using little power (d) senses how bright it is
  39. 39.What does a thermistor do? (a) smooths a wobbly supply (b) senses how hot it is (c) makes a beeping sound (d) has coloured bands
  40. 40.🧩 Which component glows using little power? (a) resistor (b) LED (c) diode (d) fuse

Answer key

  1. ampere (A)
  2. P = V × I
  3. watt (W)
  4. 8
  5. False
  6. True
  7. 6
  8. 0.5
  9. saves electricity
  10. 150
  11. 1150
  12. 1000
  13. 6
  14. 1000
  15. 5 %
  16. False
  17. 3
  18. to limit the current
  19. saves electricity
  20. 2.25
  21. 0.96
  22. 170
  23. lights up
  24. R = V ÷ I
  25. how much a part resists
  26. 72000
  27. 10
  28. False
  29. ammeter
  30. 165
  31. 10
  32. 25
  33. 2300
  34. 0.9
  35. 3
  36. False
  37. False
  38. glows using little power
  39. senses how hot it is
  40. LED

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