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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 710 · 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.🔺 A current of 40 mA flows when 18.8 V is joined across a resistor. What is its resistance (in ohms)?
  2. 2.💡 Why does an LED need a resistor in series? (a) to change its colour (b) to limit the current (c) to make it brighter (d) to store charge
  3. 3.🧾 A family uses 160 units of electricity in a month and each unit costs ₹9. What is the bill (in ₹)?
  4. 4.True or false: a thermistor is a resistance knob. (a) False (b) True
  5. 5.What does a buzzer do? (a) limits the current (b) makes a beeping sound (c) stores a little charge (d) turns a fan or wheels
  6. 6.📏 In the water-pipe picture of a circuit, resistance is like … (a) the flow of water (b) a bigger tank (c) a narrow pipe (d) the water pressure
  7. 7.🧾 A 500 W appliance runs for 2 hours. How many units (kWh) of electricity does it use? =
  8. 8.🧾 A 50 W appliance runs for 6 hours. How many units (kWh) of electricity does it use? =
  9. 9.📏 How many kilo-ohms (kΩ) is 9800 Ω? =
  10. 10.🔺 A current of 2 A flows through a 20 Ω resistor. What is the voltage across it (in volts)? =
  11. 11.🧮 Two equal 50 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  12. 12.True or false: to leave fridge door open saves electricity. (a) False (b) True
  13. 13.💡 An LED is joined to a 3 V battery through a 1000 Ω resistor; the leg next to the flat edge of its rim goes to the − side. What happens? (a) lights up (b) may burn out (c) does not light
  14. 14.🧮 A 2.5 V battery is joined to 3 Ω and 2 Ω resistors in series. What current flows (in amperes)? =
  15. 15.🧩 Which component senses how bright it is? (a) resistor (b) LDR (c) fuse (d) motor
  16. 16.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 36 Ω resistor? (a) orange-blue-brown (b) yellow-blue-black (c) blue-orange-black (d) orange-blue-black
  17. 17.📏 Which unit measures voltage? (a) ohm (Ω) (b) ampere (A) (c) volt (V) (d) watt (W)
  18. 18.🔺 A 12 V supply is joined across a 6 Ω resistor. What current flows (in amperes)? =
  19. 19.🌈 A resistor has the colour bands red, grey, black. What is its value (in ohms)?
  20. 20.True or false: a buzzer limits the current. (a) False (b) True
  21. 21.🌈 A resistor has the colour bands brown, violet, brown. What is its value (in ohms)?
  22. 22.True or false: the voltmeter measures current. (a) False (b) True
  23. 23.True or false: an LED glows using little power. (a) False (b) True
  24. 24.🔺 A current of 10 mA flows through a 150 Ω resistor. What is the voltage across it (in volts)? =
  25. 25.💡 On an LED, is the leg by the flat edge the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
  26. 26.⚡ A device works on 3 V and takes 0.5 A. What is its power (in watts)? =
  27. 27.📏 How many amperes (A) is 1230 mA? =
  28. 28.Which of these wastes electricity? (a) unplug idle chargers (b) use daylight to read (c) leave fridge door open (d) set the AC to 24 °C
  29. 29.🧮 Two equal 100 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  30. 30.True or false: a capacitor makes things spin. (a) True (b) False
  31. 31.📏 How many milliamperes (mA) is 1.69 A?
  32. 32.🧮 Resistors of 330 Ω and 100 Ω are joined in series. What is the total resistance (in ohms)?
  33. 33.🧾 A family uses 60 units of electricity in a month and each unit costs ₹5. What is the bill (in ₹)?
  34. 34.💡 An LED is joined to a 5 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
  35. 35.True or false: a potentiometer is a resistance knob. (a) True (b) False
  36. 36.🧮 Two equal 330 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  37. 37.🔺 A 4 V supply is joined across a 100 Ω resistor. What current flows (in milliamperes, mA)?
  38. 38.🧮 A 50 Ω resistor is joined in series with two equal 50 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
  39. 39.⚡ Power tells us … (a) the length of a wire (b) the colour of light (c) energy used each second (d) the size of a cell
  40. 40.🧮 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

Answer key

  1. 470
  2. to limit the current
  3. 1440
  4. False
  5. makes a beeping sound
  6. a narrow pipe
  7. 1
  8. 0.3
  9. 9.8
  10. 40
  11. 25
  12. False
  13. lights up
  14. 0.5
  15. LDR
  16. orange-blue-black
  17. volt (V)
  18. 2
  19. 28
  20. False
  21. 170
  22. False
  23. True
  24. 1.5
  25. cathode (−)
  26. 1.5
  27. 1.23
  28. leave fridge door open
  29. 50
  30. False
  31. 1690
  32. 430
  33. 300
  34. lights up
  35. True
  36. 165
  37. 40
  38. 75
  39. energy used each second
  40. less than either one

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