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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 595 · 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.

NameDateTime takenScore ___ / 40
  1. 1.💡 Does it save or waste electricity to run fans in empty rooms? (a) saves electricity (b) wastes electricity
  2. 2.🧾 A family uses 90 units of electricity in a month and each unit costs ₹9. What is the bill (in ₹)?
  3. 3.🔺 A 0.6 V supply is joined across a 6 Ω resistor. What current flows (in amperes)? =
  4. 4.🔺 In the V-I-R triangle, how do we find V? (a) V = I + R (b) V = I ÷ R (c) V = R ÷ I (d) V = I × R
  5. 5.🔺 A current of 0.5 A flows through a 20 Ω resistor. What is the voltage across it (in volts)? =
  6. 6.🔺 A current of 0.5 A flows when 3 V is joined across a resistor. What is its resistance (in ohms)?
  7. 7.🔺 A 0.5 V supply is joined across a 5 Ω resistor. What current flows (in amperes)? =
  8. 8.🧾 One “unit” on an electricity bill is … (a) 1 kilowatt-hour (kWh) (b) 1 ampere (c) 1 volt (d) 1 watt
  9. 9.🧮 Resistors of 22 Ω and 47 Ω are joined in series. What is the total resistance (in ohms)?
  10. 10.⚡ Power tells us … (a) the length of a wire (b) the size of a cell (c) energy used each second (d) the colour of light
  11. 11.⚡ A device works on 5 V and takes 1.5 A. What is its power (in watts)? =
  12. 12.💡 An LED is joined to a 6 V battery with no resistor; the leg next to the flat edge of its rim goes to the − side. What happens? (a) may burn out (b) does not light (c) lights up
  13. 13.True or false: on an LED, the shorter leg is the cathode (−). (a) True (b) False
  14. 14.True or false: voltage is measured in ohms (Ω). (a) True (b) False
  15. 15.💡 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) may burn out (b) does not light (c) lights up
  16. 16.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 70 Ω resistor? (a) grey-black-black (b) grey-violet-black (c) violet-black-brown (d) violet-black-black
  17. 17.💡 On an LED, is the longer leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
  18. 18.💡 A red LED (it uses 2 V) is joined with a 150 Ω resistor to a 2.75 V supply. What current flows (in mA)?
  19. 19.🔺 A current of 2.5 A flows when 50 V is joined across a resistor. What is its resistance (in ohms)?
  20. 20.🧮 A 100 Ω resistor is joined in series with two equal 40 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
  21. 21.💡 On an LED, is the round-side leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
  22. 22.🌈 In the resistor colour code, which number does green stand for?
  23. 23.⚡ A home appliance on the 230 V mains takes 1.5 A. What is its power (in watts)?
  24. 24.🧮 Adding another resistor in series makes the total resistance … (a) smaller (b) zero (c) bigger (d) stay the same
  25. 25.What does an LDR do? (a) beeps for an alarm (b) senses how bright it is (c) makes things spin (d) makes a beeping sound
  26. 26.🔺 A current of 0.25 A flows through a 4 Ω resistor. What is the voltage across it (in volts)? =
  27. 27.📏 Which unit measures voltage? (a) volt (V) (b) ampere (A) (c) ohm (Ω) (d) watt (W)
  28. 28.💡 An LED is joined to a 6 V battery through a 330 Ω 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
  29. 29.🔺 A 3.75 V supply is joined across a 150 Ω resistor. What current flows (in milliamperes, mA)?
  30. 30.🧮 Resistors of 50 Ω and 100 Ω are joined in series. What is the total resistance (in ohms)?
  31. 31.📏 How many amperes (A) is 400 mA? =
  32. 32.📏 Which unit measures the flow of charge? (a) watt (W) (b) ampere (A) (c) volt (V) (d) ohm (Ω)
  33. 33.True or false: on an LED, the round-side leg is the cathode (−). (a) True (b) False
  34. 34.📏 How many watts (W) is 0.8 kW?
  35. 35.🔺 A current of 20 mA flows when 6 V is joined across a resistor. What is its resistance (in ohms)?
  36. 36.🔺 A current of 10 mA flows when 2 V is joined across a resistor. What is its resistance (in ohms)?
  37. 37.🌈 A resistor has the colour bands green, yellow, yellow. What is its value in kilo-ohms (kΩ)? =
  38. 38.🧮 Two resistors in parallel give a total that is … (a) their sum (b) always zero (c) more than either one (d) less than either one
  39. 39.🧮 Two equal 10 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  40. 40.🔺 A current of 40 mA flows through a 330 Ω resistor. What is the voltage across it (in volts)? =

Answer key

  1. wastes electricity
  2. 810
  3. 0.1
  4. V = I × R
  5. 10
  6. 6
  7. 0.1
  8. 1 kilowatt-hour (kWh)
  9. 69
  10. energy used each second
  11. 7.5
  12. may burn out
  13. True
  14. False
  15. may burn out
  16. violet-black-black
  17. anode (+)
  18. 5
  19. 20
  20. 120
  21. anode (+)
  22. 5
  23. 345
  24. bigger
  25. senses how bright it is
  26. 1
  27. volt (V)
  28. lights up
  29. 25
  30. 150
  31. 0.4
  32. ampere (A)
  33. False
  34. 800
  35. 300
  36. 200
  37. 540
  38. less than either one
  39. 5
  40. 13.2

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