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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 211 · 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 40 mA flows through a 470 Ω resistor. What is the voltage across it (in volts)? =
  2. 2.🧮 Adding another resistor in series makes the total resistance … (a) smaller (b) bigger (c) zero (d) stay the same
  3. 3.📏 In the water-pipe picture of a circuit, resistance is like … (a) the water pressure (b) the flow of water (c) a narrow pipe (d) a bigger tank
  4. 4.⚡ A home appliance on the 230 V mains takes 0.5 A. What is its power (in watts)?
  5. 5.🌈 A resistor has the colour bands brown, orange, yellow. What is its value in kilo-ohms (kΩ)? =
  6. 6.🔺 A current of 0.2 A flows through a 20 Ω resistor. What is the voltage across it (in volts)? =
  7. 7.⚡ A home appliance on the 230 V mains takes 2 A. What is its power (in watts)?
  8. 8.🔺 A current of 1.5 A flows when 3 V is joined across a resistor. What is its resistance (in ohms)?
  9. 9.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 5600 Ω resistor? (a) blue-green-red (b) green-blue-brown (c) green-blue-orange (d) green-blue-red
  10. 10.🧮 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
  11. 11.⚡ A 0.75 W device works on 1.5 V. What current does it take (in amperes)? =
  12. 12.💡 A blue LED uses 3 V and should get 20 mA. It runs from a 5 V supply. What resistor (in ohms) is needed in series?
  13. 13.⚡ A device works on 5 V and takes 2 A. What is its power (in watts)? =
  14. 14.True or false: how much a part resists is measured in ohms (Ω). (a) False (b) True
  15. 15.True or false: on an LED, the round-side leg is the cathode (−). (a) True (b) False
  16. 16.🔺 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
  17. 17.🔺 A current of 20 mA flows when 6 V is joined across a resistor. What is its resistance (in ohms)?
  18. 18.🌈 A gold fourth band on a resistor means the value may be off by … (a) 25 % (b) 0 % (c) 5 % (d) 50 %
  19. 19.🔺 In the V-I-R triangle, how do we find I? (a) I = V × R (b) I = V ÷ R (c) I = V + R (d) I = R ÷ V
  20. 20.🔺 In the V-I-R triangle, how do we find R? (a) R = V × I (b) R = V ÷ I (c) R = I ÷ V (d) R = V + I
  21. 21.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 6400 Ω resistor? (a) blue-yellow-brown (b) yellow-blue-red (c) blue-yellow-red (d) blue-yellow-orange
  22. 22.🔺 A 1 V supply is joined across a 10 Ω resistor. What current flows (in amperes)? =
  23. 23.🧾 A 500 W appliance runs for 6 hours. How many units (kWh) of electricity does it use? =
  24. 24.💡 An LED is joined to a 9 V battery through a 220 Ω 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
  25. 25.📏 Which unit measures how much a part resists? (a) volt (V) (b) watt (W) (c) ampere (A) (d) ohm (Ω)
  26. 26.🌈 A resistor has the colour bands yellow, yellow, red. What is its value in kilo-ohms (kΩ)? =
  27. 27.True or false: on an LED, the shorter leg is the cathode (−). (a) False (b) True
  28. 28.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 1800 Ω resistor? (a) brown-grey-orange (b) brown-grey-red (c) grey-brown-red (d) brown-grey-brown
  29. 29.🔺 A current of 10 mA flows when 5 V is joined across a resistor. What is its resistance (in ohms)?
  30. 30.What does a thermistor do? (a) senses how hot it is (b) smooths a wobbly supply (c) senses how bright it is (d) makes a beeping sound
  31. 31.True or false: the voltmeter measures current. (a) True (b) False
  32. 32.🧩 Which component senses how bright it is? (a) resistor (b) fuse (c) LDR (d) transistor
  33. 33.💡 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
  34. 34.📏 How many kilowatts (kW) is 1200 W? =
  35. 35.⚡ Power tells us … (a) the colour of light (b) the length of a wire (c) the size of a cell (d) energy used each second
  36. 36.🔺 A current of 40 mA flows when 18.8 V is joined across a resistor. What is its resistance (in ohms)?
  37. 37.🔺 A current of 0.5 A flows through a 20 Ω resistor. What is the voltage across it (in volts)? =
  38. 38.🌈 A resistor has the colour bands brown, white, yellow. What is its value in kilo-ohms (kΩ)? =
  39. 39.💡 On an LED, is the longer leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
  40. 40.🧩 Which component boosts a small signal? (a) transistor (b) buzzer (c) capacitor (d) resistor

Answer key

  1. 18.8
  2. bigger
  3. a narrow pipe
  4. 115
  5. 130
  6. 4
  7. 460
  8. 2
  9. green-blue-red
  10. less than either one
  11. 0.5
  12. 100
  13. 10
  14. True
  15. False
  16. V = I × R
  17. 300
  18. 5 %
  19. I = V ÷ R
  20. R = V ÷ I
  21. blue-yellow-red
  22. 0.1
  23. 3
  24. does not light
  25. ohm (Ω)
  26. 4.4
  27. True
  28. brown-grey-red
  29. 500
  30. senses how hot it is
  31. False
  32. LDR
  33. may burn out
  34. 1.2
  35. energy used each second
  36. 470
  37. 10
  38. 190
  39. anode (+)
  40. transistor

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