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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 563 · 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.⚡ 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
  2. 2.📏 How many kilo-ohms (kΩ) is 4000 Ω? =
  3. 3.⚡ A 0.9 W device works on 9 V. What current does it take (in amperes)? =
  4. 4.💡 A red LED uses 2 V and should get 25 mA. It runs from a 12 V supply. What resistor (in ohms) is needed in series?
  5. 5.📏 How many milliamperes (mA) make 1 ampere? (a) 1000 (b) 100 (c) 60 (d) 10
  6. 6.⚡ A device works on 9 V and takes 0.25 A. What is its power (in watts)? =
  7. 7.🔺 A current of 0.25 A flows through a 5 Ω resistor. What is the voltage across it (in volts)? =
  8. 8.💡 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) may burn out (c) lights up
  9. 9.⚡ A device works on 24 V and takes 2 A. What is its power (in watts)? =
  10. 10.🧮 A 1.5 V battery is joined to 3 Ω and 3 Ω resistors in series. What current flows (in amperes)? =
  11. 11.⚡ A home appliance on the 230 V mains takes 4 A. What is its power (in watts)?
  12. 12.🔺 A current of 0.1 A flows through a 3 Ω resistor. What is the voltage across it (in volts)? =
  13. 13.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 13000 Ω resistor? (a) brown-orange-red (b) brown-orange-yellow (c) brown-orange-orange (d) orange-brown-orange
  14. 14.📏 Voltmeter or ammeter: which one measures voltage? (a) ammeter (b) voltmeter
  15. 15.💡 An LED is joined to a 3 V battery through a 470 Ω 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
  16. 16.🌈 A resistor has the colour bands violet, green, black. What is its value (in ohms)?
  17. 17.📏 Voltmeter or ammeter: which one is joined in series? (a) voltmeter (b) ammeter
  18. 18.🧩 A capacitor in a circuit can … (a) make light (b) measure heat (c) store charge briefly (d) spin a wheel
  19. 19.💡 Does it save or waste electricity to run fans in empty rooms? (a) saves electricity (b) wastes electricity
  20. 20.⚡ A home appliance on the 230 V mains takes 8 A. What is its power (in watts)?
  21. 21.🔺 A current of 20 mA flows through a 470 Ω resistor. What is the voltage across it (in volts)? =
  22. 22.🌈 A resistor has the colour bands orange, orange, red. What is its value in kilo-ohms (kΩ)? =
  23. 23.💡 Does it save or waste electricity to use daylight to read? (a) wastes electricity (b) saves electricity
  24. 24.🧮 Three equal 300 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  25. 25.🌈 A resistor has the colour bands grey, blue, orange. What is its value (in ohms)?
  26. 26.🧩 Which component glows using little power? (a) resistor (b) thermistor (c) diode (d) LED
  27. 27.🧩 Which part changes electrical energy into sound? (a) a buzzer (b) a resistor (c) a capacitor (d) a diode
  28. 28.🧮 A 1.5 V battery is joined to 5 Ω and 10 Ω resistors in series. What current flows (in amperes)? =
  29. 29.🔺 A current of 2.5 A flows through a 10 Ω resistor. What is the voltage across it (in volts)? =
  30. 30.⚡ A device works on 6 V and takes 2 A. What is its power (in watts)? =
  31. 31.🌈 In the resistor colour code, which number does blue stand for?
  32. 32.🧾 A family uses 170 units of electricity in a month and each unit costs ₹7. What is the bill (in ₹)?
  33. 33.💡 Why does an LED need a resistor in series? (a) to change its colour (b) to store charge (c) to make it brighter (d) to limit the current
  34. 34.🧩 Which component smooths a wobbly supply? (a) capacitor (b) resistor (c) motor (d) LDR
  35. 35.🔺 A current of 2.5 A flows through a 3 Ω resistor. What is the voltage across it (in volts)? =
  36. 36.🔺 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
  37. 37.🔺 A current of 0.5 A flows through a 5 Ω resistor. What is the voltage across it (in volts)? =
  38. 38.🧮 A 2.2 V battery is joined to 6 Ω and 5 Ω resistors in series. What current flows (in amperes)? =
  39. 39.🌈 A gold fourth band on a resistor means the value may be off by … (a) 50 % (b) 0 % (c) 25 % (d) 5 %
  40. 40.🌈 A resistor has the colour bands red, white, red. What is its value in kilo-ohms (kΩ)? =

Answer key

  1. energy used each second
  2. 4
  3. 0.1
  4. 400
  5. 1000
  6. 2.25
  7. 1.25
  8. may burn out
  9. 48
  10. 0.25
  11. 920
  12. 0.3
  13. brown-orange-orange
  14. voltmeter
  15. lights up
  16. 75
  17. ammeter
  18. store charge briefly
  19. wastes electricity
  20. 1840
  21. 9.4
  22. 3.3
  23. saves electricity
  24. 100
  25. 86000
  26. LED
  27. a buzzer
  28. 0.1
  29. 25
  30. 12
  31. 6
  32. 1190
  33. to limit the current
  34. capacitor
  35. 7.5
  36. I = V ÷ R
  37. 2.5
  38. 0.2
  39. 5 %
  40. 2.9

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