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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 918 · 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 home appliance on the 230 V mains takes 0.5 A. What is its power (in watts)?
  2. 2.🧮 Two resistors in parallel give a total that is … (a) less than either one (b) their sum (c) more than either one (d) always zero
  3. 3.🔺 A current of 0.2 A flows through an 8 Ω resistor. What is the voltage across it (in volts)? =
  4. 4.🔺 A current of 20 mA flows through a 500 Ω resistor. What is the voltage across it (in volts)? =
  5. 5.🔺 A current of 0.25 A flows when 1.25 V is joined across a resistor. What is its resistance (in ohms)?
  6. 6.🔺 In the V-I-R triangle, how do we find V? (a) V = R ÷ I (b) V = I + R (c) V = I × R (d) V = I ÷ R
  7. 7.🔺 A current of 0.1 A flows through an 8 Ω resistor. What is the voltage across it (in volts)? =
  8. 8.Which of these is measured in amperes (A)? (a) current (b) how much a part resists (c) energy used each second (d) voltage
  9. 9.💡 Does it save or waste electricity to leave fridge door open? (a) saves electricity (b) wastes electricity
  10. 10.💡 A red LED uses 2 V and should get 25 mA. It runs from a 9 V supply. What resistor (in ohms) is needed in series?
  11. 11.What does an LED do? (a) senses how bright it is (b) beeps for an alarm (c) has coloured bands (d) glows using little power
  12. 12.🔺 A current of 0.5 A flows through a 5 Ω resistor. What is the voltage across it (in volts)? =
  13. 13.🧩 Which component stores a little charge? (a) resistor (b) capacitor (c) diode (d) motor
  14. 14.🌈 A resistor has the colour bands brown, green, orange. What is its value (in ohms)?
  15. 15.🌈 A gold fourth band on a resistor means the value may be off by … (a) 25 % (b) 0 % (c) 5 % (d) 50 %
  16. 16.🧾 A family uses 50 units of electricity in a month and each unit costs ₹8. What is the bill (in ₹)?
  17. 17.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) gets bigger (b) gets smaller (c) stays the same (d) becomes zero
  18. 18.🧩 Which component limits the current? (a) thermistor (b) transistor (c) resistor (d) potentiometer
  19. 19.🔺 A current of 1.5 A flows through a 6 Ω resistor. What is the voltage across it (in volts)? =
  20. 20.📏 Which unit measures how much a part resists? (a) ohm (Ω) (b) volt (V) (c) ampere (A) (d) watt (W)
  21. 21.⚡ A device works on 12 V and takes 0.25 A. What is its power (in watts)? =
  22. 22.🧮 Three equal 30 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  23. 23.🔺 A current of 2.5 A flows through a 4 Ω resistor. What is the voltage across it (in volts)? =
  24. 24.🔺 A current of 10 mA flows through a 300 Ω resistor. What is the voltage across it (in volts)? =
  25. 25.True or false: on an LED, the longer leg is the cathode (−). (a) True (b) False
  26. 26.True or false: an LDR senses how bright it is. (a) False (b) True
  27. 27.💡 On an LED, is the longer leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
  28. 28.🔺 In the V-I-R triangle, how do we find I? (a) I = V ÷ R (b) I = V × R (c) I = V + R (d) I = R ÷ V
  29. 29.🔺 A current of 25 mA flows through a 200 Ω resistor. What is the voltage across it (in volts)? =
  30. 30.🧮 A 5 V battery is joined to 2 Ω and 8 Ω resistors in series. What current flows (in amperes)? =
  31. 31.💡 What does LED stand for? (a) light-emitting diode (b) large electric dial (c) light energy dial (d) low energy device
  32. 32.🔺 A current of 10 mA flows through a 120 Ω resistor. What is the voltage across it (in volts)? =
  33. 33.🔺 A current of 0.5 A flows when 2.5 V is joined across a resistor. What is its resistance (in ohms)?
  34. 34.🧩 Which component blows if current is high? (a) capacitor (b) motor (c) LED (d) fuse
  35. 35.🧩 Which component has coloured bands? (a) resistor (b) buzzer (c) transistor (d) capacitor
  36. 36.True or false: the push of a cell is measured in volts (V). (a) True (b) False
  37. 37.💡 What happens if an LED is put in backwards? (a) it changes colour (b) it lights brighter (c) it does not light (d) it makes a sound
  38. 38.📏 In the water-pipe picture of a circuit, current is like … (a) the water pressure (b) a narrow pipe (c) the flow of water (d) the pipe colour
  39. 39.⚡ A home appliance on the 230 V mains takes 1 A. What is its power (in watts)?
  40. 40.🧩 Which part changes electrical energy into sound? (a) a resistor (b) a capacitor (c) a diode (d) a buzzer

Answer key

  1. 115
  2. less than either one
  3. 1.6
  4. 10
  5. 5
  6. V = I × R
  7. 0.8
  8. current
  9. wastes electricity
  10. 280
  11. glows using little power
  12. 2.5
  13. capacitor
  14. 15000
  15. 5 %
  16. 400
  17. gets smaller
  18. resistor
  19. 9
  20. ohm (Ω)
  21. 3
  22. 10
  23. 10
  24. 3
  25. False
  26. True
  27. anode (+)
  28. I = V ÷ R
  29. 5
  30. 0.5
  31. light-emitting diode
  32. 1.2
  33. 5
  34. fuse
  35. resistor
  36. True
  37. it does not light
  38. the flow of water
  39. 230
  40. a buzzer

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