Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 418 · 40 questions

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.

1. 1.🔺 A current of 0.1 A flows when 1.5 V is joined across a resistor. What is its resistance (in ohms)?
2. 2.🧾 A 100 W filament bulb is swapped for a 15 W LED lamp that gives about the same light. Both would run for 8 hours. How many watt-hours (Wh) are saved?
3. 3.🔍 Which is the odd one out? (a) leave fridge door open (b) unplug idle chargers (c) use LED lamps (d) set the AC to 24 °C
4. 4.🔺 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
5. 5.True or false: on an LED, the longer leg is the anode (+). (a) True (b) False
6. 6.📏 How many amperes (A) is 430 mA? =
7. 7.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark an 8300 Ω resistor? (a) grey-orange-red (b) grey-orange-brown (c) grey-orange-orange (d) orange-grey-red
8. 8.🧩 Which part changes electrical energy into movement? (a) an LED (b) a motor (c) a fuse (d) a resistor
9. 9.🧾 One “unit” on an electricity bill is … (a) 1 kilowatt-hour (kWh) (b) 1 volt (c) 1 watt (d) 1 ampere
10. 10.📏 How many kilowatts (kW) is 4750 W? =
11. 11.🌈 A resistor has the colour bands orange, red, brown. What is its value (in ohms)?
12. 12.📏 How many kilo-ohms (kΩ) is 9400 Ω? =
13. 13.🧮 A 13 V battery is joined to 3 Ω and 10 Ω resistors in series. What current flows (in amperes)? =
14. 14.🔺 In the V-I-R triangle, how do we find R? (a) R = V × I (b) R = I ÷ V (c) R = V + I (d) R = V ÷ I
15. 15.🧮 A 220 Ω resistor is joined in series with two equal 200 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
16. 16.💡 A red LED (it uses 2 V) is joined with a 300 Ω resistor to an 8 V supply. What current flows (in mA)?
17. 17.💡 On an LED, is the leg by the flat edge the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
18. 18.📏 In the water-pipe picture of a circuit, resistance is like … (a) a narrow pipe (b) the flow of water (c) a bigger tank (d) the water pressure
19. 19.True or false: on an LED, the shorter leg is the anode (+). (a) True (b) False
20. 20.🔺 A current of 1.5 A flows through a 10 Ω resistor. What is the voltage across it (in volts)? =
21. 21.🧩 A capacitor in a circuit can … (a) spin a wheel (b) store charge briefly (c) measure heat (d) make light
22. 22.⚡ A home appliance on the 230 V mains takes 8 A. What is its power (in watts)?
23. 23.🔺 A current of 3 A flows through a 20 Ω resistor. What is the voltage across it (in volts)? =
24. 24.⚡ Power tells us … (a) the size of a cell (b) the length of a wire (c) the colour of light (d) energy used each second
25. 25.Which of these wastes electricity? (a) unplug idle chargers (b) iron one shirt at a time (c) use LED lamps (d) switch off empty rooms
26. 26.🧮 A 7 V battery is joined to 6 Ω and 8 Ω resistors in series. What current flows (in amperes)? =
27. 27.🧾 A 75 W filament bulb is swapped for a 12 W LED lamp that gives about the same light. Both would run for 7 hours. How many watt-hours (Wh) are saved?
28. 28.🌈 A gold fourth band on a resistor means the value may be off by … (a) 0 % (b) 25 % (c) 5 % (d) 50 %
29. 29.🔍 Which is the odd one out? (a) close the fridge quickly (b) iron one shirt at a time (c) switch off empty rooms (d) set the AC to 24 °C
30. 30.🔺 In the V-I-R triangle, how do we find V? (a) V = I ÷ R (b) V = R ÷ I (c) V = I + R (d) V = I × R
31. 31.⚡ An 18 W device works on 6 V. What current does it take (in amperes)? =
32. 32.⚡ A device works on 5 V and takes 0.5 A. What is its power (in watts)? =
33. 33.What does a capacitor do? (a) makes a beeping sound (b) turns a fan or wheels (c) boosts a small signal (d) stores a little charge
34. 34.🧾 Which lamp gives the same light for the least power? (a) an oil lamp (b) an LED lamp (c) a filament bulb (d) a candle
35. 35.🔺 A current of 0.5 A flows through a 5 Ω resistor. What is the voltage across it (in volts)? =
36. 36.🔺 A current of 20 mA flows through a 470 Ω resistor. What is the voltage across it (in volts)? =
37. 37.💡 Does it save or waste electricity to run fans in empty rooms? (a) wastes electricity (b) saves electricity
38. 38.🔺 A current of 0.25 A flows when 3.75 V is joined across a resistor. What is its resistance (in ohms)?
39. 39.🔺 A current of 0.25 A flows through a 5 Ω resistor. What is the voltage across it (in volts)? =
40. 40.📏 Voltmeter or ammeter: which one is joined across a part? (a) voltmeter (b) ammeter

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