Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 291 · 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 resistor has the colour bands grey, grey, orange. What is its value (in ohms)?
2. 2.🔍 Which is the odd one out? (a) switch off empty rooms (b) leave fridge door open (c) use daylight to read (d) unplug idle chargers
3. 3.💡 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) lights up (b) may burn out (c) does not light
4. 4.🌈 A resistor has the colour bands white, green, orange. What is its value in kilo-ohms (kΩ)? =
5. 5.🔍 Which is the odd one out? (a) switch off empty rooms (b) close the fridge quickly (c) use daylight to read (d) iron one shirt at a time
6. 6.🔺 A current of 1 A flows through a 12 Ω resistor. What is the voltage across it (in volts)? =
7. 7.⚡ A 9 W device works on 3 V. What current does it take (in amperes)? =
8. 8.🧮 Adding another resistor in series makes the total resistance … (a) smaller (b) zero (c) bigger (d) stay the same
9. 9.🧾 Which lamp gives the same light for the least power? (a) a candle (b) an LED lamp (c) a filament bulb (d) an oil lamp
10. 10.True or false: on an LED, the leg by the flat edge is the anode (+). (a) True (b) False
11. 11.📏 Voltmeter or ammeter: which one measures current? (a) ammeter (b) voltmeter
12. 12.🧾 A 1000 W appliance runs for 4 hours. How many units (kWh) of electricity does it use? =
13. 13.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) becomes zero (b) gets smaller (c) stays the same (d) gets bigger
14. 14.Which of these is measured in ohms (Ω)? (a) how much a part resists (b) the flow of charge (c) power (d) the push of a cell
15. 15.True or false: the voltmeter is joined across a part. (a) False (b) True
16. 16.🔺 A current of 25 mA flows through a 500 Ω resistor. What is the voltage across it (in volts)? =
17. 17.🔺 A current of 40 mA flows through a 250 Ω resistor. What is the voltage across it (in volts)? =
18. 18.What does a buzzer do? (a) limits the current (b) makes a beeping sound (c) glows using little power (d) stores a little charge
19. 19.What does a capacitor do? (a) turns a fan or wheels (b) boosts a small signal (c) blows if current is high (d) stores a little charge
20. 20.🔺 A current of 40 mA flows through a 500 Ω resistor. What is the voltage across it (in volts)? =
21. 21.📏 In the water-pipe picture of a circuit, resistance is like … (a) the flow of water (b) the water pressure (c) a narrow pipe (d) a bigger tank
22. 22.⚡ A device works on 12 V and takes 0.1 A. What is its power (in watts)? =
23. 23.🔺 A current of 0.5 A flows when 1 V is joined across a resistor. What is its resistance (in ohms)?
24. 24.🧩 Which part changes electrical energy into movement? (a) a motor (b) a resistor (c) a fuse (d) an LED
25. 25.🔺 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
26. 26.True or false: a fuse boosts a small signal. (a) False (b) True
27. 27.🌈 A gold fourth band on a resistor means the value may be off by … (a) 5 % (b) 0 % (c) 50 % (d) 25 %
28. 28.🧮 A 33 Ω resistor is joined in series with two equal 470 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
29. 29.True or false: to run fans in empty rooms wastes electricity. (a) True (b) False
30. 30.True or false: a potentiometer senses how hot it is. (a) False (b) True
31. 31.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark an 85 Ω resistor? (a) grey-green-brown (b) white-green-black (c) grey-green-black (d) green-grey-black
32. 32.⚡ A device works on 1.5 V and takes 0.5 A. What is its power (in watts)? =
33. 33.🧮 Three equal 75 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
34. 34.⚡ A home appliance on the 230 V mains takes 1.5 A. What is its power (in watts)?
35. 35.🌈 In the resistor colour code, which number does yellow stand for?
36. 36.🌈 In the resistor colour code, which number does violet stand for?
37. 37.⚡ A device works on 5 V and takes 2 A. What is its power (in watts)? =
38. 38.🧾 A 100 W appliance runs for 2 hours. How many units (kWh) of electricity does it use? =
39. 39.🌈 Which band is read first on a resistor? (a) the gold band (b) the one nearest an end (c) any band (d) the widest gap
40. 40.⚡ A home appliance on the 230 V mains takes 2 A. What is its power (in watts)?

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