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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 488 · 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 10 mA flows when 4 V is joined across a resistor. What is its resistance (in ohms)?
  2. 2.🧾 Which lamp gives the same light for the least power? (a) an oil lamp (b) a candle (c) a filament bulb (d) an LED lamp
  3. 3.🔺 A current of 1 A flows through a 4 Ω resistor. What is the voltage across it (in volts)? =
  4. 4.Which of these is measured in watts (W)? (a) the push of a cell (b) energy used each second (c) voltage (d) current
  5. 5.🧮 Resistors of 330 Ω and 330 Ω are joined in series. What is the total resistance (in ohms)?
  6. 6.True or false: to leave fridge door open wastes electricity. (a) False (b) True
  7. 7.True or false: on an LED, the leg by the flat edge is the cathode (−). (a) False (b) True
  8. 8.🌈 A resistor has the colour bands violet, grey, red. What is its value (in ohms)?
  9. 9.🧮 Adding another resistor in series makes the total resistance … (a) stay the same (b) smaller (c) bigger (d) zero
  10. 10.⚡ A device works on 9 V and takes 2 A. What is its power (in watts)? =
  11. 11.💡 On an LED, is the shorter leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
  12. 12.🔺 A current of 2 A flows when 30 V is joined across a resistor. What is its resistance (in ohms)?
  13. 13.What does a fuse do? (a) blows if current is high (b) beeps for an alarm (c) makes a beeping sound (d) boosts a small signal
  14. 14.🧮 Two equal 20 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  15. 15.🔺 A current of 20 mA flows through a 100 Ω resistor. What is the voltage across it (in volts)? =
  16. 16.🧾 A family uses 180 units of electricity in a month and each unit costs ₹8. What is the bill (in ₹)?
  17. 17.True or false: on an LED, the round-side leg is the anode (+). (a) False (b) True
  18. 18.What does a thermistor do? (a) glows using little power (b) beeps for an alarm (c) stores a little charge (d) senses how hot it is
  19. 19.True or false: a capacitor stores a little charge. (a) False (b) True
  20. 20.⚡ A 1.2 W device works on 6 V. What current does it take (in amperes)? =
  21. 21.🧮 Resistors of 10 Ω, 22 Ω, 68 Ω and 68 Ω are joined in series. What is the total resistance (in ohms)?
  22. 22.🔺 In the V-I-R triangle, how do we find V? (a) V = I ÷ R (b) V = R ÷ I (c) V = I × R (d) V = I + R
  23. 23.⚡ A 6 W device works on 3 V. What current does it take (in amperes)? =
  24. 24.🔺 A current of 20 mA flows through a 470 Ω resistor. What is the voltage across it (in volts)? =
  25. 25.📏 How many kilo-ohms (kΩ) is 4600 Ω? =
  26. 26.🌈 In the resistor colour code, which number does brown stand for?
  27. 27.True or false: on an LED, the round-side leg is the cathode (−). (a) True (b) False
  28. 28.⚡ Power tells us … (a) the length of a wire (b) the size of a cell (c) energy used each second (d) the colour of light
  29. 29.🔺 A current of 0.5 A flows through a 12 Ω resistor. What is the voltage across it (in volts)? =
  30. 30.🔺 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
  31. 31.🧩 Which component senses how hot it is? (a) motor (b) buzzer (c) diode (d) thermistor
  32. 32.🔺 A current of 40 mA flows when 20 V is joined across a resistor. What is its resistance (in ohms)?
  33. 33.🔺 A current of 10 mA flows when 3.3 V is joined across a resistor. What is its resistance (in ohms)?
  34. 34.True or false: the ammeter measures voltage. (a) True (b) False
  35. 35.🔺 A current of 1 A flows through an 8 Ω resistor. What is the voltage across it (in volts)? =
  36. 36.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) becomes zero (b) gets smaller (c) gets bigger (d) stays the same
  37. 37.🔍 Which is the odd one out? (a) switch off empty rooms (b) leave the TV on standby (c) use daylight to read (d) set the AC to 24 °C
  38. 38.🔺 A current of 20 mA flows through a 330 Ω resistor. What is the voltage across it (in volts)? =
  39. 39.True or false: on an LED, the longer leg is the cathode (−). (a) True (b) False
  40. 40.🧮 Two resistors in parallel give a total that is … (a) more than either one (b) their sum (c) always zero (d) less than either one

Answer key

  1. 400
  2. an LED lamp
  3. 4
  4. energy used each second
  5. 660
  6. True
  7. True
  8. 7800
  9. bigger
  10. 18
  11. cathode (−)
  12. 15
  13. blows if current is high
  14. 10
  15. 2
  16. 1440
  17. True
  18. senses how hot it is
  19. True
  20. 0.2
  21. 168
  22. V = I × R
  23. 2
  24. 9.4
  25. 4.6
  26. 1
  27. False
  28. energy used each second
  29. 6
  30. I = V ÷ R
  31. thermistor
  32. 500
  33. 330
  34. False
  35. 8
  36. gets smaller
  37. leave the TV on standby
  38. 6.6
  39. False
  40. less than either one

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