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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 606 · 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 colour bands (1st digit, 2nd digit, multiplier) mark a 61000 Ω resistor? (a) brown-blue-orange (b) blue-brown-orange (c) blue-brown-red (d) blue-brown-yellow
  2. 2.⚡ Which formula gives electric power? (a) P = V ÷ I (b) P = I ÷ V (c) P = V × I (d) P = V + I
  3. 3.🔺 A 0.6 V supply is joined across a 6 Ω resistor. What current flows (in amperes)? =
  4. 4.🧩 Which part changes electrical energy into movement? (a) a motor (b) a fuse (c) an LED (d) a resistor
  5. 5.🔺 In the V-I-R triangle, how do we find V? (a) V = R ÷ I (b) V = I + R (c) V = I × R (d) V = I ÷ R
  6. 6.⚡ A home appliance on the 230 V mains takes 5 A. What is its power (in watts)?
  7. 7.🔺 A current of 50 mA flows through a 300 Ω resistor. What is the voltage across it (in volts)? =
  8. 8.🔺 A 45 V supply is joined across a 15 Ω resistor. What current flows (in amperes)? =
  9. 9.What does a resistor do? (a) makes things spin (b) makes a beeping sound (c) has coloured bands (d) lets current go one way
  10. 10.True or false: the push of a cell is measured in amperes (A). (a) False (b) True
  11. 11.💡 An LED is joined to a 5 V battery with no resistor; its long leg goes to the + side and its short leg to the − side. What happens? (a) does not light (b) may burn out (c) lights up
  12. 12.💡 On an LED, is the leg by the flat edge the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
  13. 13.🧩 Which component makes things spin? (a) fuse (b) diode (c) LED (d) motor
  14. 14.Which of these wastes electricity? (a) unplug idle chargers (b) leave the TV on standby (c) close the fridge quickly (d) switch off empty rooms
  15. 15.⚡ A device works on 12 V and takes 1 A. What is its power (in watts)? =
  16. 16.🧾 A 75 W filament bulb is swapped for a 12 W LED lamp that gives about the same light. Both would run for 10 hours. How many watt-hours (Wh) are saved?
  17. 17.🔺 A current of 20 mA flows when 2 V is joined across a resistor. What is its resistance (in ohms)?
  18. 18.🔺 A current of 1.5 A flows through a 12 Ω resistor. What is the voltage across it (in volts)? =
  19. 19.Which of these is measured in amperes (A)? (a) power (b) energy used each second (c) current (d) resistance
  20. 20.🧾 A family uses 80 units of electricity in a month and each unit costs ₹7. What is the bill (in ₹)?
  21. 21.True or false: on an LED, the longer leg is the cathode (−). (a) False (b) True
  22. 22.🧾 One “unit” on an electricity bill is … (a) 1 kilowatt-hour (kWh) (b) 1 volt (c) 1 ampere (d) 1 watt
  23. 23.🧾 A 60 W filament bulb is swapped for a 9 W LED lamp that gives about the same light. Both would run for 5 hours. How many watt-hours (Wh) are saved?
  24. 24.🧩 Which component boosts a small signal? (a) capacitor (b) fuse (c) diode (d) transistor
  25. 25.🌈 A resistor has the colour bands grey, white, orange. What is its value in kilo-ohms (kΩ)? =
  26. 26.🔺 A current of 25 mA flows through a 300 Ω resistor. What is the voltage across it (in volts)? =
  27. 27.⚡ A device works on 5 V and takes 0.25 A. What is its power (in watts)? =
  28. 28.⚡ A device works on 3 V and takes 0.2 A. What is its power (in watts)? =
  29. 29.⚡ A home appliance on the 230 V mains takes 1 A. What is its power (in watts)?
  30. 30.True or false: on an LED, the leg by the flat edge is the cathode (−). (a) True (b) False
  31. 31.💡 What happens if an LED is put in backwards? (a) it changes colour (b) it lights brighter (c) it makes a sound (d) it does not light
  32. 32.What does a diode do? (a) is a resistance knob (b) senses how hot it is (c) glows using little power (d) lets current go one way
  33. 33.💡 An LED is joined to a 5 V battery with no 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
  34. 34.⚡ A 2.25 W device works on 1.5 V. What current does it take (in amperes)? =
  35. 35.💡 A red LED (it uses 2 V) is joined with a 100 Ω resistor to a 3 V supply. What current flows (in mA)?
  36. 36.🔺 A current of 0.2 A flows through a 6 Ω resistor. What is the voltage across it (in volts)? =
  37. 37.🔺 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
  38. 38.🧮 Two resistors in parallel give a total that is … (a) less than either one (b) always zero (c) their sum (d) more than either one
  39. 39.True or false: on an LED, the round-side leg is the anode (+). (a) True (b) False
  40. 40.🔍 Which is the odd one out? (a) leave fridge door open (b) use old filament bulbs (c) unplug idle chargers (d) iron one shirt at a time

Answer key

  1. blue-brown-orange
  2. P = V × I
  3. 0.1
  4. a motor
  5. V = I × R
  6. 1150
  7. 15
  8. 3
  9. has coloured bands
  10. False
  11. may burn out
  12. cathode (−)
  13. motor
  14. leave the TV on standby
  15. 12
  16. 630
  17. 100
  18. 18
  19. current
  20. 560
  21. False
  22. 1 kilowatt-hour (kWh)
  23. 255
  24. transistor
  25. 89
  26. 7.5
  27. 1.25
  28. 0.6
  29. 230
  30. True
  31. it does not light
  32. lets current go one way
  33. may burn out
  34. 1.5
  35. 10
  36. 1.2
  37. R = V ÷ I
  38. less than either one
  39. True
  40. unplug idle chargers

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