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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 235 · 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.🧾 One “unit” on an electricity bill is … (a) 1 ampere (b) 1 kilowatt-hour (kWh) (c) 1 watt (d) 1 volt
  2. 2.💡 A red LED (it uses 2 V) is joined with a 200 Ω resistor to a 3 V supply. What current flows (in mA)?
  3. 3.Which of these is measured in volts (V)? (a) power (b) how much a part resists (c) the push of a cell (d) energy used each second
  4. 4.🔺 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
  5. 5.🧾 A 75 W filament bulb is swapped for a 12 W LED lamp that gives about the same light. Both would run for 4 hours. How many watt-hours (Wh) are saved?
  6. 6.🌈 A resistor has the colour bands green, black, black. What is its value (in ohms)?
  7. 7.📏 How many kilo-ohms (kΩ) is 6300 Ω? =
  8. 8.What does an LED do? (a) is a resistance knob (b) has coloured bands (c) makes a beeping sound (d) glows using little power
  9. 9.⚡ Power tells us … (a) the colour of light (b) the size of a cell (c) the length of a wire (d) energy used each second
  10. 10.True or false: how much a part resists is measured in ohms (Ω). (a) True (b) False
  11. 11.💡 Does it save or waste electricity to use daylight to read? (a) saves electricity (b) wastes electricity
  12. 12.🔺 A 30 V supply is joined across a 12 Ω resistor. What current flows (in amperes)? =
  13. 13.🔺 A current of 25 mA flows through a 120 Ω resistor. What is the voltage across it (in volts)? =
  14. 14.💡 Why does an LED need a resistor in series? (a) to make it brighter (b) to store charge (c) to limit the current (d) to change its colour
  15. 15.🧮 Two resistors in parallel give a total that is … (a) always zero (b) less than either one (c) their sum (d) more than either one
  16. 16.Which of these saves electricity? (a) leave fridge door open (b) run fans in empty rooms (c) set the AC to 24 °C (d) leave the TV on standby
  17. 17.🧮 Two equal 470 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  18. 18.🔺 A current of 0.5 A flows through a 20 Ω resistor. What is the voltage across it (in volts)? =
  19. 19.Which of these is measured in amperes (A)? (a) the push of a cell (b) resistance (c) current (d) power
  20. 20.🔺 A 16 V supply is joined across an 8 Ω resistor. What current flows (in amperes)? =
  21. 21.True or false: the flow of charge is measured in watts (W). (a) True (b) False
  22. 22.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) gets bigger (b) stays the same (c) becomes zero (d) gets smaller
  23. 23.💡 A red LED (it uses 2 V) is joined with a 300 Ω resistor to a 6.5 V supply. What current flows (in mA)?
  24. 24.📏 Which unit measures the flow of charge? (a) ohm (Ω) (b) volt (V) (c) watt (W) (d) ampere (A)
  25. 25.🔺 A current of 10 mA flows when 3.3 V is joined across a resistor. What is its resistance (in ohms)?
  26. 26.💡 On an LED, is the round-side leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
  27. 27.True or false: a motor blows if current is high. (a) True (b) False
  28. 28.🔺 A current of 2.5 A flows through a 2 Ω resistor. What is the voltage across it (in volts)? =
  29. 29.🌈 In the resistor colour code, which number does yellow stand for?
  30. 30.🧾 A 40 W filament bulb is swapped for a 6 W LED lamp that gives about the same light. Both would run for 3 hours. How many watt-hours (Wh) are saved?
  31. 31.🔺 A current of 40 mA flows when 12 V is joined across a resistor. What is its resistance (in ohms)?
  32. 32.⚡ An 18 W device works on 12 V. What current does it take (in amperes)? =
  33. 33.🔺 A current of 0.1 A flows when 0.4 V is joined across a resistor. What is its resistance (in ohms)?
  34. 34.🔺 A current of 50 mA flows through a 300 Ω resistor. What is the voltage across it (in volts)? =
  35. 35.🔍 Which is the odd one out? (a) use daylight to read (b) run fans in empty rooms (c) iron one shirt at a time (d) use old filament bulbs
  36. 36.⚡ A home appliance on the 230 V mains takes 1.5 A. What is its power (in watts)?
  37. 37.💡 An LED is joined to a 6 V battery with no resistor; its long leg goes to the + side and its short leg to the − side. What happens? (a) does not light (b) lights up (c) may burn out
  38. 38.What does a transistor do? (a) has coloured bands (b) makes things spin (c) stores a little charge (d) boosts a small signal
  39. 39.🔺 A 7.5 V supply is joined across a 300 Ω resistor. What current flows (in milliamperes, mA)?
  40. 40.📏 In the water-pipe picture of a circuit, voltage is like … (a) the pipe colour (b) the tap handle (c) the water tank lid (d) the water pressure

Answer key

  1. 1 kilowatt-hour (kWh)
  2. 5
  3. the push of a cell
  4. V = I × R
  5. 252
  6. 50
  7. 6.3
  8. glows using little power
  9. energy used each second
  10. True
  11. saves electricity
  12. 2.5
  13. 3
  14. to limit the current
  15. less than either one
  16. set the AC to 24 °C
  17. 235
  18. 10
  19. current
  20. 2
  21. False
  22. gets smaller
  23. 15
  24. ampere (A)
  25. 330
  26. anode (+)
  27. False
  28. 5
  29. 4
  30. 102
  31. 300
  32. 1.5
  33. 4
  34. 15
  35. use daylight to read
  36. 345
  37. may burn out
  38. boosts a small signal
  39. 25
  40. the water pressure

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