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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 631 · 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.🔺 A current of 2.5 A flows when 20 V is joined across a resistor. What is its resistance (in ohms)?
  2. 2.🔺 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
  3. 3.⚡ A device works on 3 V and takes 1.5 A. What is its power (in watts)? =
  4. 4.📏 How many amperes (A) is 100 mA? =
  5. 5.⚡ Which formula gives electric power? (a) P = V + I (b) P = I ÷ V (c) P = V ÷ I (d) P = V × I
  6. 6.⚡ Power tells us … (a) the size of a cell (b) the colour of light (c) the length of a wire (d) energy used each second
  7. 7.🔺 A current of 0.1 A flows through a 4 Ω resistor. What is the voltage across it (in volts)? =
  8. 8.🔺 A current of 1.5 A flows through a 6 Ω resistor. What is the voltage across it (in volts)? =
  9. 9.🧮 Resistors of 10 Ω, 10 Ω, 330 Ω and 10 Ω are joined in series. What is the total resistance (in ohms)?
  10. 10.🌈 A gold fourth band on a resistor means the value may be off by … (a) 50 % (b) 25 % (c) 0 % (d) 5 %
  11. 11.🔺 A current of 10 mA flows when 3.3 V is joined across a resistor. What is its resistance (in ohms)?
  12. 12.🌈 Which band is read first on a resistor? (a) the one nearest an end (b) any band (c) the widest gap (d) the gold band
  13. 13.📏 How many watts (W) is 0.9 kW?
  14. 14.🧮 Resistors of 10 Ω and 47 Ω are joined in series. What is the total resistance (in ohms)?
  15. 15.🔺 A current of 0.2 A flows when 0.8 V is joined across a resistor. What is its resistance (in ohms)?
  16. 16.🧾 A 60 W filament bulb is swapped for a 9 W LED lamp that gives about the same light. Both would run for 10 hours. How many watt-hours (Wh) are saved?
  17. 17.🔺 A 3 V supply is joined across a 120 Ω resistor. What current flows (in milliamperes, mA)?
  18. 18.⚡ A 3 W device works on 1.5 V. What current does it take (in amperes)? =
  19. 19.💡 A red LED (it uses 2 V) is joined with a 200 Ω resistor to a 3 V supply. What current flows (in mA)?
  20. 20.⚡ A home appliance on the 230 V mains takes 5 A. What is its power (in watts)?
  21. 21.🔺 In the V-I-R triangle, how do we find R? (a) R = I ÷ V (b) R = V + I (c) R = V ÷ I (d) R = V × I
  22. 22.🔺 A current of 1.5 A flows when 18 V is joined across a resistor. What is its resistance (in ohms)?
  23. 23.🧾 Which lamp gives the same light for the least power? (a) an LED lamp (b) an oil lamp (c) a filament bulb (d) a candle
  24. 24.📏 How many kilo-ohms (kΩ) is 9500 Ω? =
  25. 25.🧮 Resistors of 33 Ω and 68 Ω are joined in series. What is the total resistance (in ohms)?
  26. 26.🧾 A family uses 30 units of electricity in a month and each unit costs ₹6. What is the bill (in ₹)?
  27. 27.📏 Which unit measures the flow of charge? (a) ohm (Ω) (b) volt (V) (c) ampere (A) (d) watt (W)
  28. 28.🧮 A 2 V battery is joined to 12 Ω and 8 Ω resistors in series. What current flows (in amperes)? =
  29. 29.Which of these saves electricity? (a) iron one shirt at a time (b) leave the TV on standby (c) use LED lamps (d) run fans in empty rooms
  30. 30.💡 An LED is joined to a 9 V battery with no resistor; its long leg goes to the + side and its short leg to the − side. What happens? (a) may burn out (b) lights up (c) does not light
  31. 31.What does a thermistor do? (a) limits the current (b) senses how hot it is (c) beeps for an alarm (d) makes a beeping sound
  32. 32.🧾 A 2000 W appliance runs for 5 hours. How many units (kWh) of electricity does it use? =
  33. 33.🌈 A resistor has the colour bands grey, brown, red. What is its value in kilo-ohms (kΩ)? =
  34. 34.🧩 Which component limits the current? (a) resistor (b) thermistor (c) transistor (d) motor
  35. 35.🌈 A resistor has the colour bands yellow, violet, red. What is its value in kilo-ohms (kΩ)? =
  36. 36.🔺 A current of 0.5 A flows through a 2 Ω resistor. What is the voltage across it (in volts)? =
  37. 37.🔺 A current of 50 mA flows when 23.5 V is joined across a resistor. What is its resistance (in ohms)?
  38. 38.🧮 Three equal 60 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  39. 39.What does a fuse do? (a) blows if current is high (b) stores a little charge (c) makes a beeping sound (d) limits the current
  40. 40.🔺 A 15 V supply is joined across a 6 Ω resistor. What current flows (in amperes)? =

Answer key

  1. 8
  2. I = V ÷ R
  3. 4.5
  4. 0.1
  5. P = V × I
  6. energy used each second
  7. 0.4
  8. 9
  9. 360
  10. 5 %
  11. 330
  12. the one nearest an end
  13. 900
  14. 57
  15. 4
  16. 510
  17. 25
  18. 2
  19. 5
  20. 1150
  21. R = V ÷ I
  22. 12
  23. an LED lamp
  24. 9.5
  25. 101
  26. 180
  27. ampere (A)
  28. 0.1
  29. use LED lamps
  30. may burn out
  31. senses how hot it is
  32. 10
  33. 8.1
  34. resistor
  35. 4.7
  36. 1
  37. 470
  38. 20
  39. blows if current is high
  40. 2.5

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