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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 57 · 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.📏 Voltmeter or ammeter: which one measures voltage? (a) ammeter (b) voltmeter
  2. 2.⚡ A home appliance on the 230 V mains takes 2 A. What is its power (in watts)?
  3. 3.🧾 One “unit” on an electricity bill is … (a) 1 ampere (b) 1 volt (c) 1 watt (d) 1 kilowatt-hour (kWh)
  4. 4.🧮 A 3 V battery is joined to 12 Ω and 3 Ω resistors in series. What current flows (in amperes)? =
  5. 5.🌈 A resistor has the colour bands white, orange, black. What is its value (in ohms)?
  6. 6.What does a diode do? (a) beeps for an alarm (b) lets current go one way (c) blows if current is high (d) stores a little charge
  7. 7.💡 On an LED, is the round-side leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
  8. 8.🧩 Which part changes electrical energy into movement? (a) a motor (b) an LED (c) a resistor (d) a fuse
  9. 9.💡 An LED is joined to a 9 V battery through a 330 Ω resistor; its long leg goes to the + side and its short leg to the − side. What happens? (a) lights up (b) does not light (c) may burn out
  10. 10.True or false: a potentiometer is a resistance knob. (a) False (b) True
  11. 11.⚡ A home appliance on the 230 V mains takes 4 A. What is its power (in watts)?
  12. 12.🧮 A 1.4 V battery is joined to 8 Ω and 6 Ω resistors in series. What current flows (in amperes)? =
  13. 13.🔺 A 3 V supply is joined across a 15 Ω resistor. What current flows (in amperes)? =
  14. 14.True or false: a buzzer makes a beeping sound. (a) True (b) False
  15. 15.⚡ Power tells us … (a) the length of a wire (b) the size of a cell (c) the colour of light (d) energy used each second
  16. 16.What does a fuse do? (a) makes things spin (b) makes a beeping sound (c) is a resistance knob (d) blows if current is high
  17. 17.📏 How many ohms (Ω) is 8.1 kΩ?
  18. 18.What does an LED do? (a) senses how hot it is (b) blows if current is high (c) has coloured bands (d) glows using little power
  19. 19.🧩 Which part changes electrical energy into sound? (a) a resistor (b) a buzzer (c) a capacitor (d) a diode
  20. 20.💡 Why does an LED need a resistor in series? (a) to store charge (b) to make it brighter (c) to change its colour (d) to limit the current
  21. 21.🔺 A current of 0.2 A flows through an 8 Ω resistor. What is the voltage across it (in volts)? =
  22. 22.🧾 Which lamp gives the same light for the least power? (a) a candle (b) an oil lamp (c) a filament bulb (d) an LED lamp
  23. 23.⚡ A device works on 12 V and takes 0.1 A. What is its power (in watts)? =
  24. 24.🔺 A current of 20 mA flows through a 220 Ω resistor. What is the voltage across it (in volts)? =
  25. 25.🌈 A resistor has the colour bands red, blue, brown. What is its value (in ohms)?
  26. 26.True or false: a thermistor senses how hot it is. (a) False (b) True
  27. 27.⚡ Which formula gives electric power? (a) P = I ÷ V (b) P = V × I (c) P = V ÷ I (d) P = V + I
  28. 28.⚡ A 1.5 W device works on 3 V. What current does it take (in amperes)? =
  29. 29.🔺 A current of 2.5 A flows through a 3 Ω resistor. What is the voltage across it (in volts)? =
  30. 30.🔺 A current of 20 mA flows through a 100 Ω resistor. What is the voltage across it (in volts)? =
  31. 31.🧮 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
  32. 32.What does a buzzer do? (a) glows using little power (b) smooths a wobbly supply (c) makes a beeping sound (d) limits the current
  33. 33.🌈 A resistor has the colour bands grey, black, red. What is its value in kilo-ohms (kΩ)? =
  34. 34.🌈 A gold fourth band on a resistor means the value may be off by … (a) 25 % (b) 50 % (c) 5 % (d) 0 %
  35. 35.📏 How many ohms (Ω) is 1.3 kΩ?
  36. 36.🔺 A current of 20 mA flows through a 250 Ω resistor. What is the voltage across it (in volts)? =
  37. 37.🔺 A 3 V supply is joined across a 2 Ω resistor. What current flows (in amperes)? =
  38. 38.🔺 A 5 V supply is joined across a 20 Ω resistor. What current flows (in amperes)? =
  39. 39.🔺 A current of 50 mA flows through a 100 Ω resistor. What is the voltage across it (in volts)? =
  40. 40.Which of these is measured in ohms (Ω)? (a) how much a part resists (b) current (c) energy used each second (d) power

Answer key

  1. voltmeter
  2. 460
  3. 1 kilowatt-hour (kWh)
  4. 0.2
  5. 93
  6. lets current go one way
  7. anode (+)
  8. a motor
  9. lights up
  10. True
  11. 920
  12. 0.1
  13. 0.2
  14. True
  15. energy used each second
  16. blows if current is high
  17. 8100
  18. glows using little power
  19. a buzzer
  20. to limit the current
  21. 1.6
  22. an LED lamp
  23. 1.2
  24. 4.4
  25. 260
  26. True
  27. P = V × I
  28. 0.5
  29. 7.5
  30. 2
  31. less than either one
  32. makes a beeping sound
  33. 8
  34. 5 %
  35. 1300
  36. 5
  37. 1.5
  38. 0.25
  39. 5
  40. how much a part resists

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