Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 514 · 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.📏 Which unit measures resistance? (a) watt (W) (b) ohm (Ω) (c) ampere (A) (d) volt (V)
2. 2.True or false: on an LED, the leg by the flat edge is the cathode (−). (a) True (b) False
3. 3.💡 An LED is joined to a 5 V battery through a 220 Ω resistor; its long leg goes to the − side and its short leg to the + side. What happens? (a) does not light (b) lights up (c) may burn out
4. 4.🧩 A capacitor in a circuit can … (a) measure heat (b) spin a wheel (c) make light (d) store charge briefly
5. 5.True or false: the voltmeter measures current. (a) True (b) False
6. 6.🧩 Which component smooths a wobbly supply? (a) capacitor (b) potentiometer (c) resistor (d) buzzer
7. 7.📏 Which unit measures voltage? (a) ohm (Ω) (b) ampere (A) (c) watt (W) (d) volt (V)
8. 8.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 98 Ω resistor? (a) white-grey-black (b) grey-white-black (c) white-grey-brown (d) brown-grey-black
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: an LED senses how bright it is. (a) True (b) False
11. 11.🧮 Two equal 100 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
12. 12.🔺 A 25 V supply is joined across a 10 Ω resistor. What current flows (in amperes)? =
13. 13.🔺 A current of 1 A flows through a 12 Ω resistor. What is the voltage across it (in volts)? =
14. 14.📏 How many kilo-ohms (kΩ) is 4100 Ω? =
15. 15.True or false: an LED has coloured bands. (a) False (b) True
16. 16.🌈 A resistor has the colour bands red, red, orange. What is its value (in ohms)?
17. 17.🔍 Which is the odd one out? (a) use LED lamps (b) switch off empty rooms (c) use daylight to read (d) run fans in empty rooms
18. 18.💡 What does LED stand for? (a) large electric dial (b) low energy device (c) light-emitting diode (d) light energy dial
19. 19.💡 Does it save or waste electricity to use daylight to read? (a) wastes electricity (b) saves electricity
20. 20.🔺 In the V-I-R triangle, how do we find I? (a) I = V × R (b) I = V ÷ R (c) I = R ÷ V (d) I = V + R
21. 21.🧮 A 2.75 V battery is joined to 8 Ω and 3 Ω resistors in series. What current flows (in amperes)? =
22. 22.🔺 A current of 0.5 A flows through a 15 Ω resistor. What is the voltage across it (in volts)? =
23. 23.🧾 A 100 W appliance runs for 8 hours. How many units (kWh) of electricity does it use? =
24. 24.📏 How many watts (W) is 3.5 kW?
25. 25.🔺 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
26. 26.True or false: the voltmeter is joined across a part. (a) False (b) True
27. 27.🧮 Resistors of 100 Ω and 10 Ω are joined in series. What is the total resistance (in ohms)?
28. 28.🌈 A gold fourth band on a resistor means the value may be off by … (a) 0 % (b) 5 % (c) 50 % (d) 25 %
29. 29.🧮 Three equal 15 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
30. 30.📏 Which unit measures energy used each second? (a) watt (W) (b) ohm (Ω) (c) volt (V) (d) ampere (A)
31. 31.⚡ A home appliance on the 230 V mains takes 10 A. What is its power (in watts)?
32. 32.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark an 81 Ω resistor? (a) grey-brown-black (b) white-brown-black (c) grey-brown-brown (d) brown-grey-black
33. 33.🔍 Which is the odd one out? (a) leave fridge door open (b) run fans in empty rooms (c) iron one shirt at a time (d) unplug idle chargers
34. 34.💡 What happens if an LED is put in backwards? (a) it lights brighter (b) it does not light (c) it makes a sound (d) it changes colour
35. 35.🌈 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
36. 36.Which of these is measured in watts (W)? (a) voltage (b) the push of a cell (c) current (d) energy used each second
37. 37.📏 How many kilo-ohms (kΩ) is 6600 Ω? =
38. 38.⚡ A home appliance on the 230 V mains takes 8 A. What is its power (in watts)?
39. 39.📏 How many watts (W) is 3.2 kW?
40. 40.📏 How many ohms (Ω) is 5.8 kΩ?

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