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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 937 · 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.🧮 Two equal 470 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  2. 2.True or false: on an LED, the longer leg is the cathode (−). (a) True (b) False
  3. 3.📏 How many ohms (Ω) is 3.3 kΩ?
  4. 4.🌈 A resistor has the colour bands white, brown, red. What is its value in kilo-ohms (kΩ)? =
  5. 5.💡 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)?
  6. 6.🔺 A 1.2 V supply is joined across a 120 Ω resistor. What current flows (in milliamperes, mA)?
  7. 7.What does a buzzer do? (a) has coloured bands (b) makes things spin (c) makes a beeping sound (d) senses how bright it is
  8. 8.⚡ Which formula gives electric power? (a) P = I ÷ V (b) P = V + I (c) P = V ÷ I (d) P = V × I
  9. 9.🔺 A current of 20 mA flows when 4 V is joined across a resistor. What is its resistance (in ohms)?
  10. 10.🌈 A resistor has the colour bands red, violet, red. What is its value (in ohms)?
  11. 11.⚡ A 12 W device works on 6 V. What current does it take (in amperes)? =
  12. 12.🌈 A gold fourth band on a resistor means the value may be off by … (a) 25 % (b) 0 % (c) 50 % (d) 5 %
  13. 13.Which of these saves electricity? (a) run fans in empty rooms (b) leave the TV on standby (c) use LED lamps (d) iron one shirt at a time
  14. 14.🔺 A current of 10 mA flows through a 120 Ω resistor. What is the voltage across it (in volts)? =
  15. 15.🔺 A current of 0.2 A flows when 4 V is joined across a resistor. What is its resistance (in ohms)?
  16. 16.💡 A red LED (it uses 2 V) is joined with a 300 Ω resistor to a 6.5 V supply. What current flows (in mA)?
  17. 17.🔺 A current of 20 mA flows when 6.6 V is joined across a resistor. What is its resistance (in ohms)?
  18. 18.🔺 A current of 2 A flows through a 20 Ω resistor. What is the voltage across it (in volts)? =
  19. 19.🔺 A 3 V supply is joined across a 150 Ω resistor. What current flows (in milliamperes, mA)?
  20. 20.🧮 Resistors of 50 Ω, 33 Ω, 50 Ω and 10 Ω are joined in series. What is the total resistance (in ohms)?
  21. 21.💡 What happens if an LED is put in backwards? (a) it lights brighter (b) it makes a sound (c) it changes colour (d) it does not light
  22. 22.🌈 A resistor has the colour bands brown, black, orange. What is its value in kilo-ohms (kΩ)? =
  23. 23.🔺 A current of 1 A flows when 3 V is joined across a resistor. What is its resistance (in ohms)?
  24. 24.💡 Does it save or waste electricity to switch off empty rooms? (a) saves electricity (b) wastes electricity
  25. 25.🌈 In the resistor colour code, which number does violet stand for?
  26. 26.🔺 A current of 1.5 A flows through a 2 Ω resistor. What is the voltage across it (in volts)? =
  27. 27.⚡ A home appliance on the 230 V mains takes 1 A. What is its power (in watts)?
  28. 28.🔺 A current of 40 mA flows when 6 V is joined across a resistor. What is its resistance (in ohms)?
  29. 29.🧮 Two resistors in parallel give a total that is … (a) more than either one (b) less than either one (c) always zero (d) their sum
  30. 30.🔺 A 2 V supply is joined across a 20 Ω resistor. What current flows (in amperes)? =
  31. 31.True or false: an LDR senses how bright it is. (a) True (b) False
  32. 32.⚡ A 2.25 W device works on 1.5 V. What current does it take (in amperes)? =
  33. 33.True or false: a motor is a resistance knob. (a) False (b) True
  34. 34.🌈 In the resistor colour code, which number does brown stand for?
  35. 35.🔺 A current of 50 mA flows when 6 V is joined across a resistor. What is its resistance (in ohms)?
  36. 36.🔺 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
  37. 37.📏 In the water-pipe picture of a circuit, voltage is like … (a) the water tank lid (b) the water pressure (c) the pipe colour (d) the tap handle
  38. 38.🔺 A 10 V supply is joined across a 5 Ω resistor. What current flows (in amperes)? =
  39. 39.🧾 One “unit” on an electricity bill is … (a) 1 watt (b) 1 kilowatt-hour (kWh) (c) 1 ampere (d) 1 volt
  40. 40.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark an 800 Ω resistor? (a) grey-black-black (b) grey-black-red (c) white-grey-brown (d) grey-black-brown

Answer key

  1. 235
  2. False
  3. 3300
  4. 9.1
  5. 5
  6. 10
  7. makes a beeping sound
  8. P = V × I
  9. 200
  10. 2700
  11. 2
  12. 5 %
  13. use LED lamps
  14. 1.2
  15. 20
  16. 15
  17. 330
  18. 40
  19. 20
  20. 143
  21. it does not light
  22. 10
  23. 3
  24. saves electricity
  25. 7
  26. 3
  27. 230
  28. 150
  29. less than either one
  30. 0.1
  31. True
  32. 1.5
  33. False
  34. 1
  35. 120
  36. R = V ÷ I
  37. the water pressure
  38. 2
  39. 1 kilowatt-hour (kWh)
  40. grey-black-brown

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