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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 787 · 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.🔺 In the V-I-R triangle, how do we find R? (a) R = V × I (b) R = V + I (c) R = I ÷ V (d) R = V ÷ I
  2. 2.🔺 A current of 10 mA flows through a 300 Ω resistor. What is the voltage across it (in volts)? =
  3. 3.🧮 Two resistors in parallel give a total that is … (a) their sum (b) always zero (c) less than either one (d) more than either one
  4. 4.💡 On an LED, is the leg by the flat edge the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
  5. 5.🧩 Which part changes electrical energy into movement? (a) a fuse (b) a resistor (c) a motor (d) an LED
  6. 6.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) gets smaller (b) becomes zero (c) gets bigger (d) stays the same
  7. 7.🌈 Which band is read first on a resistor? (a) any band (b) the one nearest an end (c) the gold band (d) the widest gap
  8. 8.🧮 Five equal 100 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  9. 9.⚡ Which formula gives electric power? (a) P = V × I (b) P = I ÷ V (c) P = V ÷ I (d) P = V + I
  10. 10.🌈 In the resistor colour code, which number does grey stand for?
  11. 11.🧮 Two equal 220 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  12. 12.🔺 A current of 40 mA flows through a 100 Ω resistor. What is the voltage across it (in volts)? =
  13. 13.🔺 A current of 3 A flows through a 10 Ω resistor. What is the voltage across it (in volts)? =
  14. 14.🌈 A gold fourth band on a resistor means the value may be off by … (a) 50 % (b) 25 % (c) 0 % (d) 5 %
  15. 15.💡 On an LED, is the round-side leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
  16. 16.🧩 Which component beeps for an alarm? (a) thermistor (b) fuse (c) capacitor (d) buzzer
  17. 17.💡 An LED is joined to a 9 V battery through a 220 Ω resistor; the leg next to the flat edge of its rim goes to the − side. What happens? (a) may burn out (b) lights up (c) does not light
  18. 18.📏 Voltmeter or ammeter: which one measures voltage? (a) ammeter (b) voltmeter
  19. 19.⚡ Power tells us … (a) the length of a wire (b) the colour of light (c) energy used each second (d) the size of a cell
  20. 20.💡 A red LED uses 2 V and should get 25 mA. It runs from a 6 V supply. What resistor (in ohms) is needed in series?
  21. 21.🔺 A 9.4 V supply is joined across a 470 Ω resistor. What current flows (in milliamperes, mA)?
  22. 22.📏 Voltmeter or ammeter: which one is joined in series? (a) voltmeter (b) ammeter
  23. 23.What does a motor do? (a) turns a fan or wheels (b) is a resistance knob (c) beeps for an alarm (d) blows if current is high
  24. 24.True or false: a capacitor smooths a wobbly supply. (a) False (b) True
  25. 25.🧮 Two equal 470 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  26. 26.🧩 Which component senses how bright it is? (a) motor (b) buzzer (c) LDR (d) transistor
  27. 27.Which of these is measured in watts (W)? (a) current (b) energy used each second (c) resistance (d) the push of a cell
  28. 28.📏 How many watts (W) is 0.4 kW?
  29. 29.🔺 A current of 10 mA flows when 2.5 V is joined across a resistor. What is its resistance (in ohms)?
  30. 30.🧾 A family uses 180 units of electricity in a month and each unit costs ₹7. What is the bill (in ₹)?
  31. 31.🧮 A 330 Ω resistor is joined in series with two equal 10 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
  32. 32.📏 In the water-pipe picture of a circuit, current is like … (a) a narrow pipe (b) the water pressure (c) the pipe colour (d) the flow of water
  33. 33.🔺 A 24 V supply is joined across a 12 Ω resistor. What current flows (in amperes)? =
  34. 34.Which of these is measured in watts (W)? (a) the push of a cell (b) power (c) the flow of charge (d) how much a part resists
  35. 35.True or false: a diode makes a beeping sound. (a) False (b) True
  36. 36.🔺 A current of 10 mA flows through a 100 Ω resistor. What is the voltage across it (in volts)? =
  37. 37.🧩 Which component smooths a wobbly supply? (a) diode (b) potentiometer (c) capacitor (d) buzzer
  38. 38.🌈 A resistor has the colour bands grey, yellow, red. What is its value in kilo-ohms (kΩ)? =
  39. 39.🌈 A resistor has the colour bands yellow, white, black. What is its value (in ohms)?
  40. 40.🧾 Which lamp gives the same light for the least power? (a) a filament bulb (b) a candle (c) an oil lamp (d) an LED lamp

Answer key

  1. R = V ÷ I
  2. 3
  3. less than either one
  4. cathode (−)
  5. a motor
  6. gets smaller
  7. the one nearest an end
  8. 20
  9. P = V × I
  10. 8
  11. 110
  12. 4
  13. 30
  14. 5 %
  15. anode (+)
  16. buzzer
  17. lights up
  18. voltmeter
  19. energy used each second
  20. 160
  21. 20
  22. ammeter
  23. turns a fan or wheels
  24. True
  25. 235
  26. LDR
  27. energy used each second
  28. 400
  29. 250
  30. 1260
  31. 335
  32. the flow of water
  33. 2
  34. power
  35. False
  36. 1
  37. capacitor
  38. 8.4
  39. 49
  40. an LED lamp

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