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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 142 · 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 3 V supply is joined across a 6 Ω resistor. What current flows (in amperes)? =
  2. 2.🌈 A resistor has the colour bands white, red, black. What is its value (in ohms)?
  3. 3.⚡ Power tells us … (a) the colour of light (b) the size of a cell (c) the length of a wire (d) energy used each second
  4. 4.⚡ A device works on 1.5 V and takes 3 A. What is its power (in watts)? =
  5. 5.🔺 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
  6. 6.🔺 A 4.8 V supply is joined across a 120 Ω resistor. What current flows (in milliamperes, mA)?
  7. 7.🔺 A 24 V supply is joined across a 12 Ω resistor. What current flows (in amperes)? =
  8. 8.🧾 A family uses 130 units of electricity in a month and each unit costs ₹6. What is the bill (in ₹)?
  9. 9.🧾 A 50 W appliance runs for 4 hours. How many units (kWh) of electricity does it use? =
  10. 10.🌈 In the resistor colour code, which number does brown stand for?
  11. 11.📏 How many ohms (Ω) is 6.9 kΩ?
  12. 12.📏 Which unit measures the push of a cell? (a) ohm (Ω) (b) ampere (A) (c) volt (V) (d) watt (W)
  13. 13.🔺 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
  14. 14.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) gets bigger (b) stays the same (c) becomes zero (d) gets smaller
  15. 15.What does a fuse do? (a) smooths a wobbly supply (b) blows if current is high (c) glows using little power (d) boosts a small signal
  16. 16.🔍 Which is the odd one out? (a) unplug idle chargers (b) use LED lamps (c) set the AC to 24 °C (d) run fans in empty rooms
  17. 17.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 6200 Ω resistor? (a) blue-red-red (b) red-blue-red (c) blue-red-orange (d) blue-red-brown
  18. 18.💡 A red LED (it uses 2 V) is joined with a 150 Ω resistor to a 3.5 V supply. What current flows (in mA)?
  19. 19.💡 On an LED, is the longer leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
  20. 20.💡 What happens if an LED is put in backwards? (a) it does not light (b) it changes colour (c) it makes a sound (d) it lights brighter
  21. 21.⚡ A home appliance on the 230 V mains takes 8 A. What is its power (in watts)?
  22. 22.🔺 A 20 V supply is joined across a 500 Ω resistor. What current flows (in milliamperes, mA)?
  23. 23.True or false: energy used each second is measured in watts (W). (a) False (b) True
  24. 24.🌈 A resistor has the colour bands violet, yellow, red. What is its value in kilo-ohms (kΩ)? =
  25. 25.💡 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) may burn out (b) does not light (c) lights up
  26. 26.🔺 A 0.4 V supply is joined across a 4 Ω resistor. What current flows (in amperes)? =
  27. 27.⚡ A device works on 3 V and takes 0.25 A. What is its power (in watts)? =
  28. 28.True or false: on an LED, the leg by the flat edge is the cathode (−). (a) False (b) True
  29. 29.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 190 Ω resistor? (a) brown-white-red (b) white-brown-brown (c) brown-white-black (d) brown-white-brown
  30. 30.💡 A red LED (it uses 2 V) is joined with a 150 Ω resistor to a 5 V supply. What current flows (in mA)?
  31. 31.🔺 A current of 0.1 A flows through an 8 Ω resistor. What is the voltage across it (in volts)? =
  32. 32.🧾 A 100 W appliance runs for 5 hours. How many units (kWh) of electricity does it use? =
  33. 33.🔺 A current of 40 mA flows when 8.8 V is joined across a resistor. What is its resistance (in ohms)?
  34. 34.📏 Which unit measures energy used each second? (a) ohm (Ω) (b) watt (W) (c) ampere (A) (d) volt (V)
  35. 35.🧮 Two resistors in parallel give a total that is … (a) always zero (b) their sum (c) more than either one (d) less than either one
  36. 36.🌈 Which band is read first on a resistor? (a) the one nearest an end (b) any band (c) the gold band (d) the widest gap
  37. 37.🌈 A gold fourth band on a resistor means the value may be off by … (a) 0 % (b) 5 % (c) 50 % (d) 25 %
  38. 38.True or false: on an LED, the round-side leg is the anode (+). (a) False (b) True
  39. 39.🌈 A resistor has the colour bands red, brown, brown. What is its value (in ohms)?
  40. 40.True or false: on an LED, the shorter leg is the anode (+). (a) True (b) False

Answer key

  1. 0.5
  2. 92
  3. energy used each second
  4. 4.5
  5. V = I × R
  6. 40
  7. 2
  8. 780
  9. 0.2
  10. 1
  11. 6900
  12. volt (V)
  13. R = V ÷ I
  14. gets smaller
  15. blows if current is high
  16. run fans in empty rooms
  17. blue-red-red
  18. 10
  19. anode (+)
  20. it does not light
  21. 1840
  22. 40
  23. True
  24. 7.4
  25. lights up
  26. 0.1
  27. 0.75
  28. True
  29. brown-white-brown
  30. 20
  31. 0.8
  32. 0.5
  33. 220
  34. watt (W)
  35. less than either one
  36. the one nearest an end
  37. 5 %
  38. True
  39. 210
  40. False

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