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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 976 · 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 0.1 A flows through an 8 Ω resistor. What is the voltage across it (in volts)? =
  2. 2.⚡ A home appliance on the 230 V mains takes 1 A. What is its power (in watts)?
  3. 3.🧩 Which component senses how bright it is? (a) transistor (b) thermistor (c) resistor (d) LDR
  4. 4.True or false: to use LED lamps wastes electricity. (a) True (b) False
  5. 5.💡 On an LED, is the leg by the flat edge the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
  6. 6.⚡ Power tells us … (a) the colour of light (b) energy used each second (c) the length of a wire (d) the size of a cell
  7. 7.🔺 In the V-I-R triangle, how do we find R? (a) R = I ÷ V (b) R = V + I (c) R = V × I (d) R = V ÷ I
  8. 8.💡 What does LED stand for? (a) large electric dial (b) light-emitting diode (c) light energy dial (d) low energy device
  9. 9.What does a transistor do? (a) senses how bright it is (b) blows if current is high (c) smooths a wobbly supply (d) boosts a small signal
  10. 10.🧮 Five equal 125 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  11. 11.💡 A blue LED uses 3 V and should get 10 mA. It runs from a 5 V supply. What resistor (in ohms) is needed in series?
  12. 12.🔺 A current of 2.5 A flows when 10 V is joined across a resistor. What is its resistance (in ohms)?
  13. 13.⚡ A 1.2 W device works on 6 V. What current does it take (in amperes)? =
  14. 14.💡 Does it save or waste electricity to leave the TV on standby? (a) saves electricity (b) wastes electricity
  15. 15.What does an LED do? (a) smooths a wobbly supply (b) is a resistance knob (c) beeps for an alarm (d) glows using little power
  16. 16.💡 On an LED, is the shorter leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
  17. 17.True or false: on an LED, the shorter leg is the cathode (−). (a) True (b) False
  18. 18.💡 A red LED uses 2 V and should get 25 mA. It runs from a 6 V supply. What resistor (in ohms) is needed in series?
  19. 19.🌈 In the resistor colour code, which number does black stand for?
  20. 20.📏 Which unit measures the push of a cell? (a) watt (W) (b) ohm (Ω) (c) ampere (A) (d) volt (V)
  21. 21.🧾 A family uses 100 units of electricity in a month and each unit costs ₹7. What is the bill (in ₹)?
  22. 22.🧮 Adding another resistor in series makes the total resistance … (a) zero (b) stay the same (c) bigger (d) smaller
  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 2 hours. How many watt-hours (Wh) are saved?
  24. 24.🔺 A current of 0.5 A flows through a 10 Ω resistor. What is the voltage across it (in volts)? =
  25. 25.💡 What happens if an LED is put in backwards? (a) it lights brighter (b) it changes colour (c) it does not light (d) it makes a sound
  26. 26.🧾 A 100 W filament bulb is swapped for a 15 W LED lamp that gives about the same light. Both would run for 8 hours. How many watt-hours (Wh) are saved?
  27. 27.💡 An LED is joined to a 12 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
  28. 28.🔺 A current of 1 A flows when 3 V is joined across a resistor. What is its resistance (in ohms)?
  29. 29.🧮 A 1.1 V battery is joined to 5 Ω and 6 Ω resistors in series. What current flows (in amperes)? =
  30. 30.⚡ Which formula gives electric power? (a) P = V + I (b) P = V ÷ I (c) P = I ÷ V (d) P = V × I
  31. 31.Which of these is measured in amperes (A)? (a) the flow of charge (b) resistance (c) power (d) the push of a cell
  32. 32.🧾 A family uses 20 units of electricity in a month and each unit costs ₹4. What is the bill (in ₹)?
  33. 33.🧮 A 6 V battery is joined to 3 Ω and 3 Ω resistors in series. What current flows (in amperes)? =
  34. 34.True or false: on an LED, the round-side leg is the cathode (−). (a) False (b) True
  35. 35.⚡ A 24 W device works on 12 V. What current does it take (in amperes)? =
  36. 36.💡 On an LED, is the longer leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
  37. 37.🔺 In the V-I-R triangle, how do we find V? (a) V = I ÷ R (b) V = I + R (c) V = I × R (d) V = R ÷ I
  38. 38.🔺 A current of 1 A flows through a 15 Ω resistor. What is the voltage across it (in volts)? =
  39. 39.🌈 A gold fourth band on a resistor means the value may be off by … (a) 50 % (b) 25 % (c) 0 % (d) 5 %
  40. 40.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 62 Ω resistor? (a) red-blue-black (b) blue-red-brown (c) blue-red-black (d) violet-red-black

Answer key

  1. 0.8
  2. 230
  3. LDR
  4. False
  5. cathode (−)
  6. energy used each second
  7. R = V ÷ I
  8. light-emitting diode
  9. boosts a small signal
  10. 25
  11. 200
  12. 4
  13. 0.2
  14. wastes electricity
  15. glows using little power
  16. cathode (−)
  17. True
  18. 160
  19. 0
  20. volt (V)
  21. 700
  22. bigger
  23. 102
  24. 5
  25. it does not light
  26. 680
  27. may burn out
  28. 3
  29. 0.1
  30. P = V × I
  31. the flow of charge
  32. 80
  33. 1
  34. False
  35. 2
  36. anode (+)
  37. V = I × R
  38. 15
  39. 5 %
  40. blue-red-black

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