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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 456 · 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 red LED (it uses 2 V) is joined with a 200 Ω resistor to a 6 V supply. What current flows (in mA)?
  2. 2.🔺 A 3 V supply is joined across a 120 Ω resistor. What current flows (in milliamperes, mA)?
  3. 3.⚡ A device works on 3 V and takes 1.5 A. What is its power (in watts)? =
  4. 4.💡 On an LED, is the shorter leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
  5. 5.🔍 Which is the odd one out? (a) use LED lamps (b) leave fridge door open (c) leave the TV on standby (d) iron one shirt at a time
  6. 6.⚡ Which formula gives electric power? (a) P = I ÷ V (b) P = V + I (c) P = V ÷ I (d) P = V × I
  7. 7.📏 How many kilowatts (kW) is 4400 W? =
  8. 8.🧩 Which component glows using little power? (a) motor (b) LED (c) resistor (d) buzzer
  9. 9.💡 An LED is joined to a 6 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) does not light (c) lights up
  10. 10.📏 Voltmeter or ammeter: which one measures voltage? (a) voltmeter (b) ammeter
  11. 11.💡 A red LED uses 2 V and should get 10 mA. It runs from a 5 V supply. What resistor (in ohms) is needed in series?
  12. 12.🧾 A family uses 140 units of electricity in a month and each unit costs ₹9. What is the bill (in ₹)?
  13. 13.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) stays the same (b) gets smaller (c) becomes zero (d) gets bigger
  14. 14.📏 How many milliamperes (mA) is 2.66 A?
  15. 15.🔺 A current of 50 mA flows when 5 V is joined across a resistor. What is its resistance (in ohms)?
  16. 16.True or false: how much a part resists is measured in watts (W). (a) True (b) False
  17. 17.📏 In the water-pipe picture of a circuit, current is like … (a) the pipe colour (b) a narrow pipe (c) the water pressure (d) the flow of water
  18. 18.True or false: how much a part resists is measured in ohms (Ω). (a) False (b) True
  19. 19.🌈 Which band is read first on a resistor? (a) the one nearest an end (b) the gold band (c) any band (d) the widest gap
  20. 20.🧮 A 33 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)?
  21. 21.🧩 Which part changes electrical energy into movement? (a) a resistor (b) a fuse (c) a motor (d) an LED
  22. 22.⚡ A device works on 9 V and takes 2 A. What is its power (in watts)? =
  23. 23.🧾 One “unit” on an electricity bill is … (a) 1 ampere (b) 1 volt (c) 1 kilowatt-hour (kWh) (d) 1 watt
  24. 24.⚡ Power tells us … (a) the length of a wire (b) energy used each second (c) the size of a cell (d) the colour of light
  25. 25.🌈 A resistor has the colour bands red, red, red. What is its value (in ohms)?
  26. 26.📏 Which unit measures current? (a) volt (V) (b) ohm (Ω) (c) watt (W) (d) ampere (A)
  27. 27.🔺 A current of 0.5 A flows through a 2 Ω resistor. What is the voltage across it (in volts)? =
  28. 28.🧮 Two resistors in parallel give a total that is … (a) more than either one (b) their sum (c) always zero (d) less than either one
  29. 29.💡 Does it save or waste electricity to set the AC to 24 °C? (a) saves electricity (b) wastes electricity
  30. 30.📏 How many watts (W) is 3.5 kW?
  31. 31.🧾 Which lamp gives the same light for the least power? (a) a filament bulb (b) an LED lamp (c) a candle (d) an oil lamp
  32. 32.🔺 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
  33. 33.🔺 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
  34. 34.🌈 A resistor has the colour bands green, brown, orange. What is its value in kilo-ohms (kΩ)? =
  35. 35.🧮 Two equal 50 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  36. 36.🌈 A resistor has the colour bands brown, orange, red. What is its value in kilo-ohms (kΩ)? =
  37. 37.True or false: on an LED, the shorter leg is the anode (+). (a) True (b) False
  38. 38.🔺 A 2 V supply is joined across an 8 Ω resistor. What current flows (in amperes)? =
  39. 39.True or false: an LDR boosts a small signal. (a) False (b) True
  40. 40.🧩 Which component turns a fan or wheels? (a) buzzer (b) potentiometer (c) transistor (d) motor

Answer key

  1. 20
  2. 25
  3. 4.5
  4. cathode (−)
  5. use LED lamps
  6. P = V × I
  7. 4.4
  8. LED
  9. lights up
  10. voltmeter
  11. 300
  12. 1260
  13. gets smaller
  14. 2660
  15. 100
  16. False
  17. the flow of water
  18. True
  19. the one nearest an end
  20. 58
  21. a motor
  22. 18
  23. 1 kilowatt-hour (kWh)
  24. energy used each second
  25. 2200
  26. ampere (A)
  27. 1
  28. less than either one
  29. saves electricity
  30. 3500
  31. an LED lamp
  32. R = V ÷ I
  33. I = V ÷ R
  34. 51
  35. 25
  36. 1.3
  37. False
  38. 0.25
  39. False
  40. motor

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