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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 266 · 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 resistors in parallel give a total that is … (a) more than either one (b) always zero (c) less than either one (d) their sum
  2. 2.⚡ Which formula gives electric power? (a) P = V + I (b) P = I ÷ V (c) P = V ÷ I (d) P = V × I
  3. 3.⚡ A device works on 6 V and takes 0.2 A. What is its power (in watts)? =
  4. 4.Which of these is measured in watts (W)? (a) current (b) the push of a cell (c) power (d) how much a part resists
  5. 5.🧩 A capacitor in a circuit can … (a) spin a wheel (b) store charge briefly (c) make light (d) measure heat
  6. 6.📏 Voltmeter or ammeter: which one measures voltage? (a) ammeter (b) voltmeter
  7. 7.🔺 A current of 40 mA flows through a 220 Ω resistor. What is the voltage across it (in volts)? =
  8. 8.⚡ Power tells us … (a) energy used each second (b) the length of a wire (c) the size of a cell (d) the colour of light
  9. 9.True or false: resistance is measured in watts (W). (a) False (b) True
  10. 10.🧩 Which component stores a little charge? (a) potentiometer (b) diode (c) capacitor (d) motor
  11. 11.💡 On an LED, is the round-side leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
  12. 12.🔺 A current of 25 mA flows through a 120 Ω resistor. What is the voltage across it (in volts)? =
  13. 13.🔺 A 7.5 V supply is joined across a 5 Ω resistor. What current flows (in amperes)? =
  14. 14.🔺 In the V-I-R triangle, how do we find R? (a) R = V × I (b) R = I ÷ V (c) R = V ÷ I (d) R = V + I
  15. 15.📏 How many watts (W) is 3.7 kW?
  16. 16.What does a resistor do? (a) senses how bright it is (b) has coloured bands (c) stores a little charge (d) makes a beeping sound
  17. 17.🔺 A current of 25 mA flows through a 220 Ω resistor. What is the voltage across it (in volts)? =
  18. 18.💡 Does it save or waste electricity to run fans in empty rooms? (a) saves electricity (b) wastes electricity
  19. 19.🔺 A current of 2.5 A flows through a 20 Ω resistor. What is the voltage across it (in volts)? =
  20. 20.💡 A red LED (it uses 2 V) is joined with a 200 Ω resistor to a 5 V supply. What current flows (in mA)?
  21. 21.🔺 A current of 1.5 A flows when 9 V is joined across a resistor. What is its resistance (in ohms)?
  22. 22.🌈 In the resistor colour code, which number does grey stand for?
  23. 23.🔺 A 2 V supply is joined across a 4 Ω resistor. What current flows (in amperes)? =
  24. 24.🧮 Two equal 200 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  25. 25.True or false: a thermistor stores a little charge. (a) False (b) True
  26. 26.🧮 Five equal 25 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  27. 27.🧾 A family uses 120 units of electricity in a month and each unit costs ₹9. What is the bill (in ₹)?
  28. 28.True or false: a capacitor senses how bright it is. (a) False (b) True
  29. 29.🧾 A 1500 W appliance runs for 4 hours. How many units (kWh) of electricity does it use? =
  30. 30.📏 How many amperes (A) is 2820 mA? =
  31. 31.🔺 A current of 10 mA flows through a 330 Ω resistor. What is the voltage across it (in volts)? =
  32. 32.⚡ A device works on 12 V and takes 0.5 A. What is its power (in watts)? =
  33. 33.True or false: on an LED, the longer leg is the cathode (−). (a) False (b) True
  34. 34.🔺 A 10 V supply is joined across a 20 Ω resistor. What current flows (in amperes)? =
  35. 35.🧮 A 1 V battery is joined to 2 Ω and 2 Ω resistors in series. What current flows (in amperes)? =
  36. 36.🌈 In the resistor colour code, which number does blue stand for?
  37. 37.🧩 Which part changes electrical energy into movement? (a) an LED (b) a resistor (c) a fuse (d) a motor
  38. 38.🔺 A current of 50 mA flows through a 250 Ω resistor. What is the voltage across it (in volts)? =
  39. 39.🌈 A gold fourth band on a resistor means the value may be off by … (a) 0 % (b) 50 % (c) 25 % (d) 5 %
  40. 40.🧮 Two equal 20 Ω resistors are joined in parallel. What is the total resistance (in ohms)?

Answer key

  1. less than either one
  2. P = V × I
  3. 1.2
  4. power
  5. store charge briefly
  6. voltmeter
  7. 8.8
  8. energy used each second
  9. False
  10. capacitor
  11. anode (+)
  12. 3
  13. 1.5
  14. R = V ÷ I
  15. 3700
  16. has coloured bands
  17. 5.5
  18. wastes electricity
  19. 50
  20. 15
  21. 6
  22. 8
  23. 0.5
  24. 100
  25. False
  26. 5
  27. 1080
  28. False
  29. 6
  30. 2.82
  31. 3.3
  32. 6
  33. False
  34. 0.5
  35. 0.25
  36. 6
  37. a motor
  38. 12.5
  39. 5 %
  40. 10

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