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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 141 · 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 resistor has the colour bands grey, black, black. What is its value (in ohms)?
  2. 2.⚡ A home appliance on the 230 V mains takes 1 A. What is its power (in watts)?
  3. 3.🔺 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
  4. 4.📏 How many kilowatts (kW) is 1200 W? =
  5. 5.Which of these saves electricity? (a) set the AC to 24 °C (b) leave fridge door open (c) run fans in empty rooms (d) use old filament bulbs
  6. 6.⚡ Power tells us … (a) energy used each second (b) the size of a cell (c) the length of a wire (d) the colour of light
  7. 7.📏 How many watts (W) is 0.6 kW?
  8. 8.🔺 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
  9. 9.🔺 A current of 10 mA flows through a 100 Ω resistor. What is the voltage across it (in volts)? =
  10. 10.What does a buzzer do? (a) makes a beeping sound (b) lets current go one way (c) senses how bright it is (d) stores a little charge
  11. 11.🔺 A 6 V supply is joined across a 4 Ω resistor. What current flows (in amperes)? =
  12. 12.🧮 Two resistors in parallel give a total that is … (a) their sum (b) always zero (c) more than either one (d) less than either one
  13. 13.True or false: on an LED, the shorter leg is the cathode (−). (a) True (b) False
  14. 14.True or false: the voltmeter is joined in series. (a) True (b) False
  15. 15.🔺 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
  16. 16.🔺 A current of 0.2 A flows when 1.2 V is joined across a resistor. What is its resistance (in ohms)?
  17. 17.🧾 A 200 W appliance runs for 6 hours. How many units (kWh) of electricity does it use? =
  18. 18.What does a potentiometer do? (a) is a resistance knob (b) blows if current is high (c) makes things spin (d) makes a beeping sound
  19. 19.💡 On an LED, is the shorter leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
  20. 20.🧩 Which component senses how hot it is? (a) diode (b) LED (c) thermistor (d) potentiometer
  21. 21.🔺 A current of 2 A flows when 20 V is joined across a resistor. What is its resistance (in ohms)?
  22. 22.🔺 A current of 0.2 A flows through a 10 Ω resistor. What is the voltage across it (in volts)? =
  23. 23.🧮 Resistors of 470 Ω and 47 Ω are joined in series. What is the total resistance (in ohms)?
  24. 24.True or false: the ammeter is joined in series. (a) True (b) False
  25. 25.🔺 A current of 25 mA flows through a 200 Ω resistor. What is the voltage across it (in volts)? =
  26. 26.🔍 Which is the odd one out? (a) leave the TV on standby (b) use old filament bulbs (c) iron one shirt at a time (d) switch off empty rooms
  27. 27.🌈 A resistor has the colour bands violet, brown, red. What is its value (in ohms)?
  28. 28.🔺 A current of 10 mA flows when 4.7 V is joined across a resistor. What is its resistance (in ohms)?
  29. 29.🔺 A 3 V supply is joined across a 150 Ω resistor. What current flows (in milliamperes, mA)?
  30. 30.🧾 A 200 W appliance runs for 5 hours. How many units (kWh) of electricity does it use? =
  31. 31.🌈 A resistor has the colour bands brown, red, black. What is its value (in ohms)?
  32. 32.📏 Which unit measures voltage? (a) volt (V) (b) ohm (Ω) (c) ampere (A) (d) watt (W)
  33. 33.🧩 A capacitor in a circuit can … (a) store charge briefly (b) make light (c) spin a wheel (d) measure heat
  34. 34.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 930 Ω resistor? (a) white-orange-red (b) white-orange-brown (c) orange-white-brown (d) white-orange-black
  35. 35.🔺 A current of 10 mA flows through a 470 Ω resistor. What is the voltage across it (in volts)? =
  36. 36.🌈 A gold fourth band on a resistor means the value may be off by … (a) 0 % (b) 25 % (c) 5 % (d) 50 %
  37. 37.⚡ A 3 W device works on 3 V. What current does it take (in amperes)? =
  38. 38.🌈 In the resistor colour code, which number does yellow stand for?
  39. 39.What does an LDR do? (a) turns a fan or wheels (b) beeps for an alarm (c) lets current go one way (d) senses how bright it is
  40. 40.🧮 A 10 Ω resistor is joined in series with two equal 50 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?

Answer key

  1. 80
  2. 230
  3. V = I × R
  4. 1.2
  5. set the AC to 24 °C
  6. energy used each second
  7. 600
  8. R = V ÷ I
  9. 1
  10. makes a beeping sound
  11. 1.5
  12. less than either one
  13. True
  14. False
  15. I = V ÷ R
  16. 6
  17. 1.2
  18. is a resistance knob
  19. cathode (−)
  20. thermistor
  21. 10
  22. 2
  23. 517
  24. True
  25. 5
  26. switch off empty rooms
  27. 7100
  28. 470
  29. 20
  30. 1
  31. 12
  32. volt (V)
  33. store charge briefly
  34. white-orange-brown
  35. 4.7
  36. 5 %
  37. 1
  38. 4
  39. senses how bright it is
  40. 35

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