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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 305 · 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.🧮 Three equal 30 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  2. 2.🌈 Which band is read first on a resistor? (a) the gold band (b) any band (c) the one nearest an end (d) the widest gap
  3. 3.⚡ A device works on 12 V and takes 2 A. What is its power (in watts)? =
  4. 4.🔺 A 10 V supply is joined across a 500 Ω resistor. What current flows (in milliamperes, mA)?
  5. 5.🔺 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
  6. 6.🧩 Which part changes electrical energy into movement? (a) a fuse (b) a resistor (c) a motor (d) an LED
  7. 7.🌈 A resistor has the colour bands brown, violet, red. What is its value in kilo-ohms (kΩ)? =
  8. 8.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark an 82 Ω resistor? (a) grey-red-black (b) grey-red-brown (c) white-red-black (d) red-grey-black
  9. 9.⚡ A home appliance on the 230 V mains takes 0.5 A. What is its power (in watts)?
  10. 10.🔺 A 5 V supply is joined across a 2 Ω resistor. What current flows (in amperes)? =
  11. 11.🌈 In the resistor colour code, which number does black stand for?
  12. 12.📏 How many ohms (Ω) is 2.4 kΩ?
  13. 13.True or false: a diode blows if current is high. (a) True (b) False
  14. 14.🧾 A 50 W appliance runs for 8 hours. How many units (kWh) of electricity does it use? =
  15. 15.🧾 A family uses 130 units of electricity in a month and each unit costs ₹9. What is the bill (in ₹)?
  16. 16.True or false: a buzzer makes a beeping sound. (a) False (b) True
  17. 17.True or false: to run fans in empty rooms wastes electricity. (a) False (b) True
  18. 18.💡 An LED is joined to a 6 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
  19. 19.📏 In the water-pipe picture of a circuit, current is like … (a) the flow of water (b) the pipe colour (c) a narrow pipe (d) the water pressure
  20. 20.💡 Does it save or waste electricity to use daylight to read? (a) saves electricity (b) wastes electricity
  21. 21.🧩 Which component limits the current? (a) LED (b) potentiometer (c) resistor (d) capacitor
  22. 22.🧩 Which part changes electrical energy into sound? (a) a resistor (b) a capacitor (c) a diode (d) a buzzer
  23. 23.💡 A red LED (it uses 2 V) is joined with a 300 Ω resistor to a 3.5 V supply. What current flows (in mA)?
  24. 24.💡 A red LED (it uses 2 V) is joined with a 150 Ω resistor to a 3.5 V supply. What current flows (in mA)?
  25. 25.🔺 A current of 1 A flows through a 5 Ω resistor. What is the voltage across it (in volts)? =
  26. 26.True or false: current is measured in ohms (Ω). (a) False (b) True
  27. 27.🔺 A current of 1.5 A flows through a 15 Ω resistor. What is the voltage across it (in volts)? =
  28. 28.🧮 Two resistors in parallel give a total that is … (a) their sum (b) more than either one (c) always zero (d) less than either one
  29. 29.🧮 A 1.6 V battery is joined to 5 Ω and 3 Ω resistors in series. What current flows (in amperes)? =
  30. 30.🧮 Adding another resistor in series makes the total resistance … (a) zero (b) bigger (c) smaller (d) stay the same
  31. 31.⚡ A 0.6 W device works on 6 V. What current does it take (in amperes)? =
  32. 32.🌈 A resistor has the colour bands yellow, red, black. What is its value (in ohms)?
  33. 33.🔺 A current of 50 mA flows when 15 V is joined across a resistor. What is its resistance (in ohms)?
  34. 34.🔺 A current of 10 mA flows when 1 V is joined across a resistor. What is its resistance (in ohms)?
  35. 35.🔺 A current of 0.25 A flows when 0.5 V is joined across a resistor. What is its resistance (in ohms)?
  36. 36.🌈 A gold fourth band on a resistor means the value may be off by … (a) 50 % (b) 25 % (c) 5 % (d) 0 %
  37. 37.True or false: to switch off empty rooms saves electricity. (a) True (b) False
  38. 38.🔺 A 3.75 V supply is joined across a 15 Ω resistor. What current flows (in amperes)? =
  39. 39.🔍 Which is the odd one out? (a) use old filament bulbs (b) iron one shirt at a time (c) use daylight to read (d) leave fridge door open
  40. 40.💡 An LED is joined to a 3 V battery through a 1000 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

Answer key

  1. 10
  2. the one nearest an end
  3. 24
  4. 20
  5. R = V ÷ I
  6. a motor
  7. 1.7
  8. grey-red-black
  9. 115
  10. 2.5
  11. 0
  12. 2400
  13. False
  14. 0.4
  15. 1170
  16. True
  17. True
  18. may burn out
  19. the flow of water
  20. saves electricity
  21. resistor
  22. a buzzer
  23. 5
  24. 10
  25. 5
  26. False
  27. 22.5
  28. less than either one
  29. 0.2
  30. bigger
  31. 0.1
  32. 42
  33. 300
  34. 100
  35. 2
  36. 5 %
  37. True
  38. 0.25
  39. use daylight to read
  40. lights up

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