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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 170 · 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.🧾 One “unit” on an electricity bill is … (a) 1 ampere (b) 1 watt (c) 1 volt (d) 1 kilowatt-hour (kWh)
  2. 2.💡 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?
  3. 3.📏 How many milliamperes (mA) is 0.91 A?
  4. 4.🔺 A current of 3 A flows through a 6 Ω resistor. What is the voltage across it (in volts)? =
  5. 5.🔺 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
  6. 6.📏 Which unit measures how much a part resists? (a) watt (W) (b) volt (V) (c) ampere (A) (d) ohm (Ω)
  7. 7.🔺 A current of 10 mA flows through a 220 Ω resistor. What is the voltage across it (in volts)? =
  8. 8.🧮 Two equal 50 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  9. 9.⚡ A home appliance on the 230 V mains takes 5 A. What is its power (in watts)?
  10. 10.🔺 A current of 40 mA flows when 4.8 V is joined across a resistor. What is its resistance (in ohms)?
  11. 11.🧾 A family uses 100 units of electricity in a month and each unit costs ₹7. What is the bill (in ₹)?
  12. 12.⚡ A 6 W device works on 24 V. What current does it take (in amperes)? =
  13. 13.Which of these is measured in watts (W)? (a) power (b) the flow of charge (c) current (d) how much a part resists
  14. 14.True or false: a potentiometer is a resistance knob. (a) True (b) False
  15. 15.🧩 Which part changes electrical energy into movement? (a) a fuse (b) an LED (c) a motor (d) a resistor
  16. 16.⚡ A device works on 9 V and takes 0.2 A. What is its power (in watts)? =
  17. 17.🧩 Which component senses how bright it is? (a) fuse (b) buzzer (c) LDR (d) transistor
  18. 18.Which of these is measured in volts (V)? (a) the flow of charge (b) power (c) the push of a cell (d) energy used each second
  19. 19.💡 A red LED (it uses 2 V) is joined with a 100 Ω resistor to a 4 V supply. What current flows (in mA)?
  20. 20.⚡ A device works on 1.5 V and takes 0.2 A. What is its power (in watts)? =
  21. 21.⚡ A home appliance on the 230 V mains takes 0.5 A. What is its power (in watts)?
  22. 22.⚡ A home appliance on the 230 V mains takes 8 A. What is its power (in watts)?
  23. 23.📏 Voltmeter or ammeter: which one measures voltage? (a) ammeter (b) voltmeter
  24. 24.🔺 In the V-I-R triangle, how do we find I? (a) I = V + R (b) I = R ÷ V (c) I = V × R (d) I = V ÷ R
  25. 25.📏 How many kilowatts (kW) is 2600 W? =
  26. 26.💡 On an LED, is the longer leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
  27. 27.True or false: the ammeter is joined across a part. (a) True (b) False
  28. 28.💡 A red LED (it uses 2 V) is joined with a 100 Ω resistor to a 2.5 V supply. What current flows (in mA)?
  29. 29.True or false: on an LED, the longer leg is the cathode (−). (a) True (b) False
  30. 30.🧩 Which component is a resistance knob? (a) LED (b) LDR (c) diode (d) potentiometer
  31. 31.🌈 A resistor has the colour bands red, orange, black. What is its value (in ohms)?
  32. 32.📏 Which unit measures current? (a) volt (V) (b) watt (W) (c) ohm (Ω) (d) ampere (A)
  33. 33.⚡ A device works on 3 V and takes 0.1 A. What is its power (in watts)? =
  34. 34.True or false: a transistor has coloured bands. (a) False (b) True
  35. 35.🔺 A current of 2.5 A flows through an 8 Ω resistor. What is the voltage across it (in volts)? =
  36. 36.📏 Voltmeter or ammeter: which one is joined in series? (a) ammeter (b) voltmeter
  37. 37.What does a transistor do? (a) smooths a wobbly supply (b) makes things spin (c) senses how bright it is (d) boosts a small signal
  38. 38.What does a resistor do? (a) senses how bright it is (b) has coloured bands (c) boosts a small signal (d) stores a little charge
  39. 39.True or false: on an LED, the round-side leg is the cathode (−). (a) True (b) False
  40. 40.💡 What does LED stand for? (a) low energy device (b) light energy dial (c) light-emitting diode (d) large electric dial

Answer key

  1. 1 kilowatt-hour (kWh)
  2. 240
  3. 910
  4. 18
  5. V = I × R
  6. ohm (Ω)
  7. 2.2
  8. 25
  9. 1150
  10. 120
  11. 700
  12. 0.25
  13. power
  14. True
  15. a motor
  16. 1.8
  17. LDR
  18. the push of a cell
  19. 20
  20. 0.3
  21. 115
  22. 1840
  23. voltmeter
  24. I = V ÷ R
  25. 2.6
  26. anode (+)
  27. False
  28. 5
  29. False
  30. potentiometer
  31. 23
  32. ampere (A)
  33. 0.3
  34. False
  35. 20
  36. ammeter
  37. boosts a small signal
  38. has coloured bands
  39. False
  40. light-emitting diode

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