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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 451 · 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 20 Ω resistor is joined in series with two equal 20 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
  2. 2.⚡ A 0.15 W device works on 1.5 V. What current does it take (in amperes)? =
  3. 3.🧮 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
  4. 4.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) gets smaller (b) gets bigger (c) becomes zero (d) stays the same
  5. 5.🔺 A 2.5 V supply is joined across a 250 Ω resistor. What current flows (in milliamperes, mA)?
  6. 6.💡 On an LED, is the longer leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
  7. 7.⚡ A device works on 1.5 V and takes 0.2 A. What is its power (in watts)? =
  8. 8.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 740 Ω resistor? (a) violet-yellow-red (b) yellow-violet-brown (c) violet-yellow-black (d) violet-yellow-brown
  9. 9.🔺 A current of 1.5 A flows through a 15 Ω resistor. What is the voltage across it (in volts)? =
  10. 10.True or false: a transistor smooths a wobbly supply. (a) True (b) False
  11. 11.🔺 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
  12. 12.What does a diode do? (a) is a resistance knob (b) blows if current is high (c) stores a little charge (d) lets current go one way
  13. 13.🧮 Resistors of 50 Ω, 470 Ω and 100 Ω are joined in series. What is the total resistance (in ohms)?
  14. 14.🧮 Two equal 220 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  15. 15.💡 Why does an LED need a resistor in series? (a) to limit the current (b) to store charge (c) to make it brighter (d) to change its colour
  16. 16.🧮 Resistors of 220 Ω, 20 Ω and 20 Ω are joined in series. What is the total resistance (in ohms)?
  17. 17.⚡ Power tells us … (a) energy used each second (b) the length of a wire (c) the colour of light (d) the size of a cell
  18. 18.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 29000 Ω resistor? (a) white-red-orange (b) red-white-orange (c) red-white-red (d) red-white-yellow
  19. 19.🧮 Two equal 20 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  20. 20.🔺 A 0.5 V supply is joined across a 5 Ω resistor. What current flows (in amperes)? =
  21. 21.💡 A red LED (it uses 2 V) is joined with a 200 Ω resistor to a 5 V supply. What current flows (in mA)?
  22. 22.🔺 A 37.5 V supply is joined across a 15 Ω resistor. What current flows (in amperes)? =
  23. 23.🔺 A 2 V supply is joined across a 20 Ω resistor. What current flows (in amperes)? =
  24. 24.🔺 A current of 25 mA flows through a 250 Ω resistor. What is the voltage across it (in volts)? =
  25. 25.📏 How many ohms make 1 kilo-ohm (kΩ)? (a) 10 (b) 100 (c) 1024 (d) 1000
  26. 26.🔺 A current of 1 A flows when 12 V is joined across a resistor. What is its resistance (in ohms)?
  27. 27.💡 An LED is joined to a 12 V battery with no resistor; its long leg goes to the + side and its short leg to the − side. What happens? (a) may burn out (b) does not light (c) lights up
  28. 28.🔺 In the V-I-R triangle, how do we find I? (a) I = V ÷ R (b) I = V + R (c) I = R ÷ V (d) I = V × R
  29. 29.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 7000 Ω resistor? (a) violet-black-red (b) grey-violet-red (c) violet-black-brown (d) violet-black-orange
  30. 30.🔺 A current of 0.5 A flows when 5 V is joined across a resistor. What is its resistance (in ohms)?
  31. 31.💡 A blue LED uses 3 V and should get 10 mA. It runs from a 12 V supply. What resistor (in ohms) is needed in series?
  32. 32.🔺 A current of 3 A flows through a 6 Ω resistor. What is the voltage across it (in volts)? =
  33. 33.True or false: to use daylight to read saves electricity. (a) False (b) True
  34. 34.🔺 A 7.5 V supply is joined across a 300 Ω resistor. What current flows (in milliamperes, mA)?
  35. 35.Which of these is measured in volts (V)? (a) the flow of charge (b) current (c) voltage (d) resistance
  36. 36.🧾 A 200 W appliance runs for 6 hours. How many units (kWh) of electricity does it use? =
  37. 37.🔺 A current of 10 mA flows through a 400 Ω resistor. What is the voltage across it (in volts)? =
  38. 38.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 60000 Ω resistor? (a) blue-black-yellow (b) violet-blue-orange (c) blue-black-red (d) blue-black-orange
  39. 39.Which of these is measured in ohms (Ω)? (a) current (b) the flow of charge (c) energy used each second (d) resistance
  40. 40.🔺 A 1.5 V supply is joined across a 6 Ω resistor. What current flows (in amperes)? =

Answer key

  1. 30
  2. 0.1
  3. less than either one
  4. gets smaller
  5. 10
  6. anode (+)
  7. 0.3
  8. violet-yellow-brown
  9. 22.5
  10. False
  11. R = V ÷ I
  12. lets current go one way
  13. 620
  14. 110
  15. to limit the current
  16. 260
  17. energy used each second
  18. red-white-orange
  19. 10
  20. 0.1
  21. 15
  22. 2.5
  23. 0.1
  24. 6.25
  25. 1000
  26. 12
  27. may burn out
  28. I = V ÷ R
  29. violet-black-red
  30. 10
  31. 900
  32. 18
  33. True
  34. 25
  35. voltage
  36. 1.2
  37. 4
  38. blue-black-orange
  39. resistance
  40. 0.25

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