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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 836 · 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.💡 Does it save or waste electricity to iron one shirt at a time? (a) wastes electricity (b) saves electricity
  2. 2.🔺 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
  3. 3.🔺 A current of 25 mA flows when 10 V is joined across a resistor. What is its resistance (in ohms)?
  4. 4.🔺 A 5 V supply is joined across a 200 Ω resistor. What current flows (in milliamperes, mA)?
  5. 5.Which of these wastes electricity? (a) use old filament bulbs (b) set the AC to 24 °C (c) close the fridge quickly (d) switch off empty rooms
  6. 6.True or false: a potentiometer limits the current. (a) True (b) False
  7. 7.🧮 Five equal 100 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  8. 8.🔺 A current of 0.1 A flows through a 15 Ω resistor. What is the voltage across it (in volts)? =
  9. 9.True or false: a thermistor boosts a small signal. (a) False (b) True
  10. 10.🔺 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
  11. 11.🧩 Which part changes electrical energy into sound? (a) a resistor (b) a capacitor (c) a diode (d) a buzzer
  12. 12.🔺 A 3 V supply is joined across a 150 Ω resistor. What current flows (in milliamperes, mA)?
  13. 13.True or false: the voltmeter measures current. (a) False (b) True
  14. 14.🌈 A gold fourth band on a resistor means the value may be off by … (a) 25 % (b) 50 % (c) 0 % (d) 5 %
  15. 15.🔺 A 2 V supply is joined across a 100 Ω resistor. What current flows (in milliamperes, mA)?
  16. 16.⚡ A home appliance on the 230 V mains takes 10 A. What is its power (in watts)?
  17. 17.Which of these is measured in volts (V)? (a) current (b) the flow of charge (c) voltage (d) energy used each second
  18. 18.📏 How many amperes (A) is 1810 mA? =
  19. 19.🌈 In the resistor colour code, which number does green stand for?
  20. 20.💡 Does it save or waste electricity to use daylight to read? (a) wastes electricity (b) saves electricity
  21. 21.🔍 Which is the odd one out? (a) leave fridge door open (b) use old filament bulbs (c) close the fridge quickly (d) iron one shirt at a time
  22. 22.🧮 Three equal 60 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  23. 23.🌈 A resistor has the colour bands green, red, orange. What is its value in kilo-ohms (kΩ)? =
  24. 24.What does a potentiometer do? (a) beeps for an alarm (b) is a resistance knob (c) blows if current is high (d) lets current go one way
  25. 25.🧩 Which component blows if current is high? (a) buzzer (b) potentiometer (c) fuse (d) motor
  26. 26.True or false: a thermistor stores a little charge. (a) True (b) False
  27. 27.💡 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) does not light (b) lights up (c) may burn out
  28. 28.⚡ Which formula gives electric power? (a) P = V ÷ I (b) P = V + I (c) P = I ÷ V (d) P = V × I
  29. 29.🔺 A current of 10 mA flows through a 500 Ω resistor. What is the voltage across it (in volts)? =
  30. 30.True or false: energy used each second is measured in ohms (Ω). (a) False (b) True
  31. 31.🧮 A 33 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)?
  32. 32.🧮 A 1.1 V battery is joined to 5 Ω and 6 Ω resistors in series. What current flows (in amperes)? =
  33. 33.Which of these wastes electricity? (a) use daylight to read (b) unplug idle chargers (c) switch off empty rooms (d) leave the TV on standby
  34. 34.What does a transistor do? (a) boosts a small signal (b) lets current go one way (c) makes things spin (d) has coloured bands
  35. 35.🔺 A 3 V supply is joined across a 300 Ω resistor. What current flows (in milliamperes, mA)?
  36. 36.📏 In the water-pipe picture of a circuit, current is like … (a) the pipe colour (b) the flow of water (c) a narrow pipe (d) the water pressure
  37. 37.🔺 A 24 V supply is joined across a 12 Ω resistor. What current flows (in amperes)? =
  38. 38.Which of these wastes electricity? (a) close the fridge quickly (b) use LED lamps (c) run fans in empty rooms (d) unplug idle chargers
  39. 39.💡 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)?
  40. 40.Which of these is measured in amperes (A)? (a) voltage (b) power (c) energy used each second (d) the flow of charge

Answer key

  1. wastes electricity
  2. gets smaller
  3. 400
  4. 25
  5. use old filament bulbs
  6. False
  7. 20
  8. 1.5
  9. False
  10. R = V ÷ I
  11. a buzzer
  12. 20
  13. False
  14. 5 %
  15. 20
  16. 2300
  17. voltage
  18. 1.81
  19. 5
  20. saves electricity
  21. close the fridge quickly
  22. 20
  23. 52
  24. is a resistance knob
  25. fuse
  26. False
  27. lights up
  28. P = V × I
  29. 5
  30. False
  31. 43
  32. 0.1
  33. leave the TV on standby
  34. boosts a small signal
  35. 10
  36. the flow of water
  37. 2
  38. run fans in empty rooms
  39. 15
  40. the flow of charge

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