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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 765 · 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.🔺 A current of 1 A flows when 5 V is joined across a resistor. What is its resistance (in ohms)?
  2. 2.Which of these saves electricity? (a) use old filament bulbs (b) leave the TV on standby (c) switch off empty rooms (d) run fans in empty rooms
  3. 3.📏 Which unit measures the push of a cell? (a) watt (W) (b) volt (V) (c) ampere (A) (d) ohm (Ω)
  4. 4.🧮 Two resistors in parallel give a total that is … (a) more than either one (b) always zero (c) less than either one (d) their sum
  5. 5.Which of these is measured in volts (V)? (a) voltage (b) energy used each second (c) power (d) current
  6. 6.📏 How many ohms (Ω) is 3.4 kΩ?
  7. 7.🧩 A capacitor in a circuit can … (a) store charge briefly (b) spin a wheel (c) make light (d) measure heat
  8. 8.🔺 A current of 1 A flows when 3 V is joined across a resistor. What is its resistance (in ohms)?
  9. 9.True or false: energy used each second is measured in watts (W). (a) True (b) False
  10. 10.📏 How many amperes (A) is 480 mA? =
  11. 11.🔺 A 5 V supply is joined across a 200 Ω resistor. What current flows (in milliamperes, mA)?
  12. 12.📏 Voltmeter or ammeter: which one is joined in series? (a) voltmeter (b) ammeter
  13. 13.🔺 A current of 25 mA flows through a 470 Ω resistor. What is the voltage across it (in volts)? =
  14. 14.🧾 One “unit” on an electricity bill is … (a) 1 ampere (b) 1 kilowatt-hour (kWh) (c) 1 volt (d) 1 watt
  15. 15.⚡ A home appliance on the 230 V mains takes 2 A. What is its power (in watts)?
  16. 16.📏 How many ohms (Ω) is 2.5 kΩ?
  17. 17.🔺 A current of 50 mA flows through a 400 Ω resistor. What is the voltage across it (in volts)? =
  18. 18.💡 An LED is joined to a 6 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
  19. 19.🔺 A current of 0.2 A flows through a 20 Ω resistor. What is the voltage across it (in volts)? =
  20. 20.🔺 A current of 20 mA flows when 9.4 V is joined across a resistor. What is its resistance (in ohms)?
  21. 21.🔺 A current of 0.1 A flows through a 12 Ω resistor. What is the voltage across it (in volts)? =
  22. 22.🧩 Which part changes electrical energy into movement? (a) a motor (b) a fuse (c) an LED (d) a resistor
  23. 23.🔺 A 1.5 V supply is joined across a 150 Ω resistor. What current flows (in milliamperes, mA)?
  24. 24.📏 How many ohms make 1 kilo-ohm (kΩ)? (a) 1000 (b) 10 (c) 1024 (d) 100
  25. 25.📏 How many amperes (A) is 880 mA? =
  26. 26.🧮 Four equal 100 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  27. 27.📏 How many watts (W) is 1 kW?
  28. 28.🧩 Which component has coloured bands? (a) resistor (b) motor (c) buzzer (d) diode
  29. 29.📏 Voltmeter or ammeter: which one is joined across a part? (a) voltmeter (b) ammeter
  30. 30.📏 In the water-pipe picture of a circuit, resistance is like … (a) the flow of water (b) a narrow pipe (c) the water pressure (d) a bigger tank
  31. 31.Which of these saves electricity? (a) leave fridge door open (b) iron one shirt at a time (c) set the AC to 24 °C (d) leave the TV on standby
  32. 32.🔺 A current of 25 mA flows through a 220 Ω resistor. What is the voltage across it (in volts)? =
  33. 33.⚡ A device works on 5 V and takes 0.2 A. What is its power (in watts)? =
  34. 34.🔺 A current of 50 mA flows through a 100 Ω resistor. What is the voltage across it (in volts)? =
  35. 35.⚡ A device works on 3 V and takes 1 A. What is its power (in watts)? =
  36. 36.⚡ A home appliance on the 230 V mains takes 5 A. What is its power (in watts)?
  37. 37.🔺 A current of 25 mA flows through a 100 Ω resistor. What is the voltage across it (in volts)? =
  38. 38.What does a diode do? (a) lets current go one way (b) blows if current is high (c) smooths a wobbly supply (d) turns a fan or wheels
  39. 39.🔺 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
  40. 40.⚡ A device works on 24 V and takes 1.5 A. What is its power (in watts)? =

Answer key

  1. 5
  2. switch off empty rooms
  3. volt (V)
  4. less than either one
  5. voltage
  6. 3400
  7. store charge briefly
  8. 3
  9. True
  10. 0.48
  11. 25
  12. ammeter
  13. 11.75
  14. 1 kilowatt-hour (kWh)
  15. 460
  16. 2500
  17. 20
  18. does not light
  19. 4
  20. 470
  21. 1.2
  22. a motor
  23. 10
  24. 1000
  25. 0.88
  26. 25
  27. 1000
  28. resistor
  29. voltmeter
  30. a narrow pipe
  31. set the AC to 24 °C
  32. 5.5
  33. 1
  34. 5
  35. 3
  36. 1150
  37. 2.5
  38. lets current go one way
  39. R = V ÷ I
  40. 36

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