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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 568 · 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 10 V supply is joined across a 400 Ω resistor. What current flows (in milliamperes, mA)?
  2. 2.🔺 An 18.8 V supply is joined across a 470 Ω resistor. What current flows (in milliamperes, mA)?
  3. 3.Which of these is measured in volts (V)? (a) energy used each second (b) voltage (c) resistance (d) the flow of charge
  4. 4.Which of these is measured in ohms (Ω)? (a) the push of a cell (b) voltage (c) how much a part resists (d) the flow of charge
  5. 5.📏 Voltmeter or ammeter: which one measures current? (a) voltmeter (b) ammeter
  6. 6.True or false: a thermistor turns a fan or wheels. (a) False (b) True
  7. 7.🔺 A 2 V supply is joined across an 8 Ω resistor. What current flows (in amperes)? =
  8. 8.Which of these is measured in watts (W)? (a) power (b) current (c) the flow of charge (d) the push of a cell
  9. 9.🔺 A current of 25 mA flows when 2.5 V is joined across a resistor. What is its resistance (in ohms)?
  10. 10.🧮 A 150 Ω resistor is joined in series with two equal 40 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
  11. 11.🔺 A current of 25 mA flows through a 470 Ω resistor. What is the voltage across it (in volts)? =
  12. 12.💡 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)?
  13. 13.📏 Which unit measures the push of a cell? (a) watt (W) (b) volt (V) (c) ohm (Ω) (d) ampere (A)
  14. 14.⚡ A device works on 24 V and takes 3 A. What is its power (in watts)? =
  15. 15.🔺 A current of 0.2 A flows through a 10 Ω resistor. What is the voltage across it (in volts)? =
  16. 16.⚡ Which formula gives electric power? (a) P = V × I (b) P = I ÷ V (c) P = V ÷ I (d) P = V + I
  17. 17.What does a potentiometer do? (a) smooths a wobbly supply (b) blows if current is high (c) stores a little charge (d) is a resistance knob
  18. 18.💡 An LED is joined to a 3 V battery through a 1000 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
  19. 19.🔺 In the V-I-R triangle, how do we find I? (a) I = R ÷ V (b) I = V × R (c) I = V ÷ R (d) I = V + R
  20. 20.🌈 Which band is read first on a resistor? (a) the widest gap (b) any band (c) the one nearest an end (d) the gold band
  21. 21.🧩 Which component limits the current? (a) LDR (b) resistor (c) diode (d) thermistor
  22. 22.🔺 A 1.6 V supply is joined across an 8 Ω resistor. What current flows (in amperes)? =
  23. 23.💡 A red LED (it uses 2 V) is joined with a 100 Ω resistor to a 3 V supply. What current flows (in mA)?
  24. 24.🔺 A 4.8 V supply is joined across a 120 Ω resistor. What current flows (in milliamperes, mA)?
  25. 25.🔺 A current of 10 mA flows through a 330 Ω resistor. What is the voltage across it (in volts)? =
  26. 26.🔺 A 6 V supply is joined across a 3 Ω resistor. What current flows (in amperes)? =
  27. 27.🔺 A current of 1.5 A flows when 4.5 V is joined across a resistor. What is its resistance (in ohms)?
  28. 28.Which of these saves electricity? (a) leave fridge door open (b) close the fridge quickly (c) run fans in empty rooms (d) leave the TV on standby
  29. 29.🔺 A current of 40 mA flows through a 120 Ω resistor. What is the voltage across it (in volts)? =
  30. 30.🌈 A resistor has the colour bands red, white, brown. What is its value (in ohms)?
  31. 31.Which of these wastes electricity? (a) iron one shirt at a time (b) switch off empty rooms (c) set the AC to 24 °C (d) use LED lamps
  32. 32.📏 Which unit measures energy used each second? (a) volt (V) (b) ampere (A) (c) ohm (Ω) (d) watt (W)
  33. 33.🧾 A family uses 190 units of electricity in a month and each unit costs ₹4. What is the bill (in ₹)?
  34. 34.🧮 Two resistors in parallel give a total that is … (a) less than either one (b) always zero (c) their sum (d) more than either one
  35. 35.🧮 Two equal 50 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  36. 36.📏 Which unit measures power? (a) ohm (Ω) (b) watt (W) (c) ampere (A) (d) volt (V)
  37. 37.📏 How many ohms make 1 kilo-ohm (kΩ)? (a) 100 (b) 10 (c) 1000 (d) 1024
  38. 38.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) becomes zero (b) gets smaller (c) gets bigger (d) stays the same
  39. 39.⚡ A device works on 24 V and takes 1 A. What is its power (in watts)? =
  40. 40.🔺 A current of 3 A flows through a 3 Ω resistor. What is the voltage across it (in volts)? =

Answer key

  1. 25
  2. 40
  3. voltage
  4. how much a part resists
  5. ammeter
  6. False
  7. 0.25
  8. power
  9. 100
  10. 170
  11. 11.75
  12. 5
  13. volt (V)
  14. 72
  15. 2
  16. P = V × I
  17. is a resistance knob
  18. lights up
  19. I = V ÷ R
  20. the one nearest an end
  21. resistor
  22. 0.2
  23. 10
  24. 40
  25. 3.3
  26. 2
  27. 3
  28. close the fridge quickly
  29. 4.8
  30. 290
  31. iron one shirt at a time
  32. watt (W)
  33. 760
  34. less than either one
  35. 25
  36. watt (W)
  37. 1000
  38. gets smaller
  39. 24
  40. 9

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