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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 881 · 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 50 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  2. 2.True or false: a resistor beeps for an alarm. (a) False (b) True
  3. 3.🌈 A resistor has the colour bands brown, white, brown. What is its value (in ohms)?
  4. 4.🧩 Which part changes electrical energy into sound? (a) a capacitor (b) a diode (c) a resistor (d) a buzzer
  5. 5.🌈 Which band is read first on a resistor? (a) the gold band (b) the one nearest an end (c) any band (d) the widest gap
  6. 6.🧾 A family uses 130 units of electricity in a month and each unit costs ₹8. What is the bill (in ₹)?
  7. 7.True or false: a thermistor senses how hot it is. (a) False (b) True
  8. 8.Which of these is measured in amperes (A)? (a) the push of a cell (b) current (c) resistance (d) power
  9. 9.🔺 A current of 0.5 A flows through a 20 Ω resistor. What is the voltage across it (in volts)? =
  10. 10.🔺 A current of 20 mA flows when 2 V is joined across a resistor. What is its resistance (in ohms)?
  11. 11.📏 How many amperes (A) is 870 mA? =
  12. 12.🔺 A 0.2 V supply is joined across a 2 Ω resistor. What current flows (in amperes)? =
  13. 13.🔺 A current of 50 mA flows through a 150 Ω resistor. What is the voltage across it (in volts)? =
  14. 14.True or false: the push of a cell is measured in volts (V). (a) True (b) False
  15. 15.⚡ Power tells us … (a) the size of a cell (b) energy used each second (c) the colour of light (d) the length of a wire
  16. 16.🧮 Resistors of 22 Ω and 150 Ω are joined in series. What is the total resistance (in ohms)?
  17. 17.🌈 In the resistor colour code, which number does grey stand for?
  18. 18.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 41000 Ω resistor? (a) yellow-brown-yellow (b) brown-yellow-orange (c) yellow-brown-orange (d) yellow-brown-red
  19. 19.💡 Why does an LED need a resistor in series? (a) to store charge (b) to make it brighter (c) to change its colour (d) to limit the current
  20. 20.🔺 A current of 3 A flows through a 4 Ω resistor. What is the voltage across it (in volts)? =
  21. 21.📏 In the water-pipe picture of a circuit, voltage is like … (a) the water pressure (b) the water tank lid (c) the pipe colour (d) the tap handle
  22. 22.🔺 A current of 50 mA flows through a 470 Ω resistor. What is the voltage across it (in volts)? =
  23. 23.🧮 Resistors of 68 Ω and 68 Ω are joined in series. What is the total resistance (in ohms)?
  24. 24.💡 On an LED, is the round-side leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
  25. 25.🧩 Which component turns a fan or wheels? (a) transistor (b) fuse (c) diode (d) motor
  26. 26.💡 A blue LED uses 3 V and should get 25 mA. It runs from a 9 V supply. What resistor (in ohms) is needed in series?
  27. 27.What does a buzzer do? (a) blows if current is high (b) makes a beeping sound (c) senses how hot it is (d) smooths a wobbly supply
  28. 28.🔺 A 0.5 V supply is joined across a 5 Ω resistor. What current flows (in amperes)? =
  29. 29.🔺 A current of 40 mA flows through a 500 Ω resistor. What is the voltage across it (in volts)? =
  30. 30.🧮 Two resistors in parallel give a total that is … (a) always zero (b) their sum (c) less than either one (d) more than either one
  31. 31.🔺 A 1.2 V supply is joined across a 120 Ω resistor. What current flows (in milliamperes, mA)?
  32. 32.🧮 Two equal 20 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  33. 33.🌈 A gold fourth band on a resistor means the value may be off by … (a) 25 % (b) 50 % (c) 5 % (d) 0 %
  34. 34.💡 A red LED uses 2 V and should get 25 mA. It runs from a 5 V supply. What resistor (in ohms) is needed in series?
  35. 35.🔺 A current of 0.5 A flows through a 4 Ω resistor. What is the voltage across it (in volts)? =
  36. 36.📏 Voltmeter or ammeter: which one measures voltage? (a) voltmeter (b) ammeter
  37. 37.⚡ A device works on 3 V and takes 1.5 A. What is its power (in watts)? =
  38. 38.🔺 In the V-I-R triangle, how do we find V? (a) V = R ÷ I (b) V = I ÷ R (c) V = I × R (d) V = I + R
  39. 39.📏 How many kilo-ohms (kΩ) is 2400 Ω? =
  40. 40.📏 How many kilowatts (kW) is 250 W? =

Answer key

  1. 25
  2. False
  3. 190
  4. a buzzer
  5. the one nearest an end
  6. 1040
  7. True
  8. current
  9. 10
  10. 100
  11. 0.87
  12. 0.1
  13. 7.5
  14. True
  15. energy used each second
  16. 172
  17. 8
  18. yellow-brown-orange
  19. to limit the current
  20. 12
  21. the water pressure
  22. 23.5
  23. 136
  24. anode (+)
  25. motor
  26. 240
  27. makes a beeping sound
  28. 0.1
  29. 20
  30. less than either one
  31. 10
  32. 10
  33. 5 %
  34. 120
  35. 2
  36. voltmeter
  37. 4.5
  38. V = I × R
  39. 2.4
  40. 0.25

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