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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 880 · 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.📏 Which unit measures resistance? (a) ampere (A) (b) volt (V) (c) ohm (Ω) (d) watt (W)
  2. 2.🧮 Two equal 330 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  3. 3.🔺 A current of 1 A flows through a 5 Ω resistor. What is the voltage across it (in volts)? =
  4. 4.🔺 A 4.4 V supply is joined across a 220 Ω resistor. What current flows (in milliamperes, mA)?
  5. 5.📏 How many watts (W) is 2.3 kW?
  6. 6.💡 On an LED, is the shorter leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
  7. 7.Which of these saves electricity? (a) run fans in empty rooms (b) use daylight to read (c) leave the TV on standby (d) leave fridge door open
  8. 8.True or false: energy used each second is measured in amperes (A). (a) True (b) False
  9. 9.🔺 In the V-I-R triangle, how do we find I? (a) I = R ÷ V (b) I = V × R (c) I = V + R (d) I = V ÷ R
  10. 10.⚡ A home appliance on the 230 V mains takes 4 A. What is its power (in watts)?
  11. 11.📏 Which unit measures how much a part resists? (a) ohm (Ω) (b) watt (W) (c) volt (V) (d) ampere (A)
  12. 12.⚡ A 4.5 W device works on 9 V. What current does it take (in amperes)? =
  13. 13.🔺 A current of 20 mA flows when 4 V is joined across a resistor. What is its resistance (in ohms)?
  14. 14.True or false: on an LED, the round-side leg is the anode (+). (a) True (b) False
  15. 15.🌈 Which band is read first on a resistor? (a) the gold band (b) any band (c) the one nearest an end (d) the widest gap
  16. 16.🌈 A resistor has the colour bands blue, green, brown. What is its value (in ohms)?
  17. 17.🧮 Resistors of 150 Ω, 33 Ω and 330 Ω are joined in series. What is the total resistance (in ohms)?
  18. 18.⚡ A home appliance on the 230 V mains takes 5 A. What is its power (in watts)?
  19. 19.📏 Which unit measures the push of a cell? (a) watt (W) (b) ampere (A) (c) volt (V) (d) ohm (Ω)
  20. 20.🧾 One “unit” on an electricity bill is … (a) 1 watt (b) 1 volt (c) 1 kilowatt-hour (kWh) (d) 1 ampere
  21. 21.🔍 Which is the odd one out? (a) leave fridge door open (b) use old filament bulbs (c) set the AC to 24 °C (d) leave the TV on standby
  22. 22.Which of these is measured in ohms (Ω)? (a) energy used each second (b) power (c) voltage (d) resistance
  23. 23.⚡ Power tells us … (a) the size of a cell (b) energy used each second (c) the colour of light (d) the length of a wire
  24. 24.📏 How many milliamperes (mA) is 2 A?
  25. 25.What does a capacitor do? (a) makes a beeping sound (b) lets current go one way (c) senses how bright it is (d) smooths a wobbly supply
  26. 26.💡 On an LED, is the round-side leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
  27. 27.🧮 Two resistors in parallel give a total that is … (a) more than either one (b) their sum (c) less than either one (d) always zero
  28. 28.🧮 A 4 V battery is joined to 5 Ω and 3 Ω resistors in series. What current flows (in amperes)? =
  29. 29.🧩 Which component glows using little power? (a) motor (b) potentiometer (c) LED (d) diode
  30. 30.🔺 A current of 0.25 A flows when 0.75 V is joined across a resistor. What is its resistance (in ohms)?
  31. 31.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 4400 Ω resistor? (a) yellow-yellow-brown (b) yellow-yellow-orange (c) yellow-green-red (d) yellow-yellow-red
  32. 32.🌈 A resistor has the colour bands orange, orange, black. What is its value (in ohms)?
  33. 33.🔺 A 5 V supply is joined across a 200 Ω resistor. What current flows (in milliamperes, mA)?
  34. 34.🧩 Which component makes a beeping sound? (a) buzzer (b) LDR (c) fuse (d) potentiometer
  35. 35.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark an 8700 Ω resistor? (a) grey-violet-brown (b) grey-violet-red (c) violet-grey-red (d) grey-violet-orange
  36. 36.🧾 A 500 W appliance runs for 8 hours. How many units (kWh) of electricity does it use? =
  37. 37.🔺 A current of 0.2 A flows through a 15 Ω resistor. What is the voltage across it (in volts)? =
  38. 38.Which of these wastes electricity? (a) use LED lamps (b) switch off empty rooms (c) run fans in empty rooms (d) set the AC to 24 °C
  39. 39.🔺 In the V-I-R triangle, how do we find R? (a) R = V × I (b) R = V ÷ I (c) R = V + I (d) R = I ÷ V
  40. 40.⚡ A 1.5 W device works on 6 V. What current does it take (in amperes)? =

Answer key

  1. ohm (Ω)
  2. 165
  3. 5
  4. 20
  5. 2300
  6. cathode (−)
  7. use daylight to read
  8. False
  9. I = V ÷ R
  10. 920
  11. ohm (Ω)
  12. 0.5
  13. 200
  14. True
  15. the one nearest an end
  16. 650
  17. 513
  18. 1150
  19. volt (V)
  20. 1 kilowatt-hour (kWh)
  21. set the AC to 24 °C
  22. resistance
  23. energy used each second
  24. 2000
  25. smooths a wobbly supply
  26. anode (+)
  27. less than either one
  28. 0.5
  29. LED
  30. 3
  31. yellow-yellow-red
  32. 33
  33. 25
  34. buzzer
  35. grey-violet-red
  36. 4
  37. 3
  38. run fans in empty rooms
  39. R = V ÷ I
  40. 0.25

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