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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 965 · 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 device works on 24 V and takes 3 A. What is its power (in watts)? =
  2. 2.⚡ A home appliance on the 230 V mains takes 2 A. What is its power (in watts)?
  3. 3.🔺 A current of 0.25 A flows through a 2 Ω resistor. What is the voltage across it (in volts)? =
  4. 4.🧮 Four equal 40 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  5. 5.🔺 A current of 2.5 A flows when 5 V is joined across a resistor. What is its resistance (in ohms)?
  6. 6.💡 On an LED, is the shorter leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
  7. 7.💡 An LED is joined to a 5 V battery with no resistor; the leg next to the flat edge of its rim goes to the − side. What happens? (a) does not light (b) lights up (c) may burn out
  8. 8.⚡ A 12 W device works on 6 V. What current does it take (in amperes)? =
  9. 9.True or false: on an LED, the longer leg is the anode (+). (a) False (b) True
  10. 10.True or false: to unplug idle chargers saves electricity. (a) True (b) False
  11. 11.🧾 A family uses 80 units of electricity in a month and each unit costs ₹5. What is the bill (in ₹)?
  12. 12.🌈 A gold fourth band on a resistor means the value may be off by … (a) 0 % (b) 50 % (c) 5 % (d) 25 %
  13. 13.🌈 In the resistor colour code, which number does brown stand for?
  14. 14.What does a fuse do? (a) lets current go one way (b) beeps for an alarm (c) senses how bright it is (d) blows if current is high
  15. 15.🧮 A 2.6 V battery is joined to 8 Ω and 5 Ω resistors in series. What current flows (in amperes)? =
  16. 16.🧮 Resistors of 150 Ω, 50 Ω and 47 Ω are joined in series. What is the total resistance (in ohms)?
  17. 17.🔍 Which is the odd one out? (a) use LED lamps (b) use old filament bulbs (c) close the fridge quickly (d) unplug idle chargers
  18. 18.🔺 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
  19. 19.🔺 A current of 2 A flows through a 10 Ω resistor. What is the voltage across it (in volts)? =
  20. 20.🧩 Which part changes electrical energy into sound? (a) a capacitor (b) a resistor (c) a buzzer (d) a diode
  21. 21.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) stays the same (b) gets smaller (c) gets bigger (d) becomes zero
  22. 22.🧩 A capacitor in a circuit can … (a) measure heat (b) store charge briefly (c) make light (d) spin a wheel
  23. 23.What does a transistor do? (a) has coloured bands (b) boosts a small signal (c) limits the current (d) senses how bright it is
  24. 24.🧮 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)?
  25. 25.🧮 Two resistors in parallel give a total that is … (a) their sum (b) always zero (c) more than either one (d) less than either one
  26. 26.🧮 Two equal 220 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  27. 27.True or false: the push of a cell is measured in watts (W). (a) True (b) False
  28. 28.📏 Which unit measures the push of a cell? (a) ampere (A) (b) watt (W) (c) ohm (Ω) (d) volt (V)
  29. 29.🌈 A resistor has the colour bands grey, blue, orange. What is its value (in ohms)?
  30. 30.🔺 A current of 2.5 A flows through a 4 Ω resistor. What is the voltage across it (in volts)? =
  31. 31.🔺 A current of 0.2 A flows through a 4 Ω resistor. What is the voltage across it (in volts)? =
  32. 32.🔺 An 18.8 V supply is joined across a 470 Ω resistor. What current flows (in milliamperes, mA)?
  33. 33.True or false: a thermistor makes a beeping sound. (a) True (b) False
  34. 34.True or false: on an LED, the leg by the flat edge is the anode (+). (a) False (b) True
  35. 35.🌈 A resistor has the colour bands orange, black, orange. What is its value in kilo-ohms (kΩ)? =
  36. 36.⚡ 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
  37. 37.Which of these saves electricity? (a) run fans in empty rooms (b) use LED lamps (c) iron one shirt at a time (d) leave the TV on standby
  38. 38.True or false: the push of a cell is measured in volts (V). (a) True (b) False
  39. 39.What does an LED do? (a) senses how bright it is (b) limits the current (c) is a resistance knob (d) glows using little power
  40. 40.🧾 A 1000 W appliance runs for 6 hours. How many units (kWh) of electricity does it use? =

Answer key

  1. 72
  2. 460
  3. 0.5
  4. 10
  5. 2
  6. cathode (−)
  7. may burn out
  8. 2
  9. True
  10. True
  11. 400
  12. 5 %
  13. 1
  14. blows if current is high
  15. 0.2
  16. 247
  17. use old filament bulbs
  18. I = V ÷ R
  19. 20
  20. a buzzer
  21. gets smaller
  22. store charge briefly
  23. boosts a small signal
  24. 75
  25. less than either one
  26. 110
  27. False
  28. volt (V)
  29. 86000
  30. 10
  31. 0.8
  32. 40
  33. False
  34. False
  35. 30
  36. energy used each second
  37. use LED lamps
  38. True
  39. glows using little power
  40. 6

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