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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 535 · 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.📏 In the water-pipe picture of a circuit, resistance is like … (a) a bigger tank (b) a narrow pipe (c) the water pressure (d) the flow of water
  2. 2.🔺 A current of 2.5 A flows through a 4 Ω resistor. What is the voltage across it (in volts)? =
  3. 3.📏 Voltmeter or ammeter: which one is joined in series? (a) ammeter (b) voltmeter
  4. 4.Which of these wastes electricity? (a) use daylight to read (b) iron one shirt at a time (c) use LED lamps (d) close the fridge quickly
  5. 5.💡 On an LED, is the shorter leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
  6. 6.💡 What happens if an LED is put in backwards? (a) it changes colour (b) it makes a sound (c) it does not light (d) it lights brighter
  7. 7.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 50 Ω resistor? (a) green-black-brown (b) blue-green-black (c) blue-black-black (d) green-black-black
  8. 8.What does a transistor do? (a) makes things spin (b) smooths a wobbly supply (c) glows using little power (d) boosts a small signal
  9. 9.True or false: an LDR beeps for an alarm. (a) False (b) True
  10. 10.🔺 A current of 3 A flows through a 5 Ω resistor. What is the voltage across it (in volts)? =
  11. 11.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 9600 Ω resistor? (a) white-blue-orange (b) white-blue-brown (c) blue-white-red (d) white-blue-red
  12. 12.🧩 Which component blows if current is high? (a) thermistor (b) motor (c) resistor (d) fuse
  13. 13.⚡ A device works on 9 V and takes 1 A. What is its power (in watts)? =
  14. 14.⚡ A 1.2 W device works on 12 V. What current does it take (in amperes)? =
  15. 15.⚡ A device works on 12 V and takes 0.1 A. What is its power (in watts)? =
  16. 16.📏 How many ohms (Ω) is 8.7 kΩ?
  17. 17.Which of these is measured in amperes (A)? (a) power (b) the push of a cell (c) current (d) energy used each second
  18. 18.💡 Does it save or waste electricity to use daylight to read? (a) wastes electricity (b) saves electricity
  19. 19.What does a diode do? (a) stores a little charge (b) lets current go one way (c) boosts a small signal (d) senses how bright it is
  20. 20.🧮 Two equal 100 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  21. 21.🧾 A 2000 W appliance runs for 2 hours. How many units (kWh) of electricity does it use? =
  22. 22.True or false: on an LED, the leg by the flat edge is the anode (+). (a) False (b) True
  23. 23.🔺 A current of 10 mA flows through a 150 Ω resistor. What is the voltage across it (in volts)? =
  24. 24.⚡ Which formula gives electric power? (a) P = I ÷ V (b) P = V + I (c) P = V × I (d) P = V ÷ I
  25. 25.💡 An LED is joined to a 9 V battery through a 1000 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
  26. 26.What does an LDR do? (a) blows if current is high (b) has coloured bands (c) senses how bright it is (d) smooths a wobbly supply
  27. 27.💡 Does it save or waste electricity to unplug idle chargers? (a) saves electricity (b) wastes electricity
  28. 28.What does a thermistor do? (a) glows using little power (b) lets current go one way (c) senses how hot it is (d) makes a beeping sound
  29. 29.📏 Which unit measures energy used each second? (a) watt (W) (b) volt (V) (c) ampere (A) (d) ohm (Ω)
  30. 30.🔺 A current of 0.2 A flows through a 15 Ω resistor. What is the voltage across it (in volts)? =
  31. 31.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) gets bigger (b) becomes zero (c) stays the same (d) gets smaller
  32. 32.🔺 In the V-I-R triangle, how do we find R? (a) R = V × I (b) R = I ÷ V (c) R = V + I (d) R = V ÷ I
  33. 33.True or false: the ammeter measures voltage. (a) False (b) True
  34. 34.🔺 A current of 1 A flows through a 2 Ω resistor. What is the voltage across it (in volts)? =
  35. 35.🔍 Which is the odd one out? (a) unplug idle chargers (b) switch off empty rooms (c) run fans in empty rooms (d) use LED lamps
  36. 36.True or false: energy used each second is measured in amperes (A). (a) True (b) False
  37. 37.🧾 One “unit” on an electricity bill is … (a) 1 kilowatt-hour (kWh) (b) 1 watt (c) 1 ampere (d) 1 volt
  38. 38.💡 On an LED, is the longer leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
  39. 39.🧮 Three equal 60 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  40. 40.🔺 A current of 25 mA flows through a 500 Ω resistor. What is the voltage across it (in volts)? =

Answer key

  1. a narrow pipe
  2. 10
  3. ammeter
  4. iron one shirt at a time
  5. cathode (−)
  6. it does not light
  7. green-black-black
  8. boosts a small signal
  9. False
  10. 15
  11. white-blue-red
  12. fuse
  13. 9
  14. 0.1
  15. 1.2
  16. 8700
  17. current
  18. saves electricity
  19. lets current go one way
  20. 50
  21. 4
  22. False
  23. 1.5
  24. P = V × I
  25. lights up
  26. senses how bright it is
  27. saves electricity
  28. senses how hot it is
  29. watt (W)
  30. 3
  31. gets smaller
  32. R = V ÷ I
  33. False
  34. 2
  35. run fans in empty rooms
  36. False
  37. 1 kilowatt-hour (kWh)
  38. anode (+)
  39. 20
  40. 12.5

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