Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 554 · 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.📏 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
2. 2.🧮 A 470 Ω resistor is joined in series with two equal 100 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
3. 3.🧮 Five equal 100 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
4. 4.True or false: on an LED, the longer leg is the cathode (−). (a) False (b) True
5. 5.🧮 Four equal 200 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
6. 6.⚡ Which formula gives electric power? (a) P = V × I (b) P = V ÷ I (c) P = I ÷ V (d) P = V + I
7. 7.🌈 A gold fourth band on a resistor means the value may be off by … (a) 50 % (b) 0 % (c) 25 % (d) 5 %
8. 8.🔺 A 12 V supply is joined across a 4 Ω resistor. What current flows (in amperes)? =
9. 9.🔺 A current of 25 mA flows through a 330 Ω resistor. What is the voltage across it (in volts)? =
10. 10.📏 How many ohms (Ω) is 1.9 kΩ?
11. 11.🧾 One “unit” on an electricity bill is … (a) 1 watt (b) 1 volt (c) 1 kilowatt-hour (kWh) (d) 1 ampere
12. 12.🌈 Which band is read first on a resistor? (a) the widest gap (b) the one nearest an end (c) the gold band (d) any band
13. 13.🌈 In the resistor colour code, which number does blue stand for?
14. 14.🧮 Adding another resistor in series makes the total resistance … (a) zero (b) bigger (c) smaller (d) stay the same
15. 15.🌈 A resistor has the colour bands blue, orange, red. What is its value (in ohms)?
16. 16.🔺 A 0.6 V supply is joined across a 3 Ω resistor. What current flows (in amperes)? =
17. 17.📏 How many milliamperes (mA) make 1 ampere? (a) 60 (b) 10 (c) 100 (d) 1000
18. 18.🧩 A capacitor in a circuit can … (a) spin a wheel (b) make light (c) measure heat (d) store charge briefly
19. 19.🧮 A 68 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)?
20. 20.🔺 A current of 3 A flows when 60 V is joined across a resistor. What is its resistance (in ohms)?
21. 21.🔺 A current of 0.2 A flows when 1 V is joined across a resistor. What is its resistance (in ohms)?
22. 22.🧾 Which lamp gives the same light for the least power? (a) a candle (b) an LED lamp (c) an oil lamp (d) a filament bulb
23. 23.True or false: the voltmeter measures current. (a) True (b) False
24. 24.What does a resistor do? (a) stores a little charge (b) senses how hot it is (c) boosts a small signal (d) limits the current
25. 25.📏 How many amperes (A) is 1070 mA? =
26. 26.🧮 A 6 V battery is joined to 4 Ω and 2 Ω resistors in series. What current flows (in amperes)? =
27. 27.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 730 Ω resistor? (a) orange-violet-brown (b) violet-orange-brown (c) violet-orange-black (d) violet-orange-red
28. 28.True or false: a diode stores a little charge. (a) True (b) False
29. 29.🧮 Two equal 20 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
30. 30.🧩 Which component limits the current? (a) motor (b) resistor (c) LDR (d) potentiometer
31. 31.📏 How many milliamperes (mA) is 2.28 A?
32. 32.🧩 Which component is a resistance knob? (a) potentiometer (b) LED (c) capacitor (d) motor
33. 33.💡 On an LED, is the leg by the flat edge the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
34. 34.What does a transistor do? (a) boosts a small signal (b) blows if current is high (c) stores a little charge (d) is a resistance knob
35. 35.⚡ A home appliance on the 230 V mains takes 5 A. What is its power (in watts)?
36. 36.📏 Which unit measures voltage? (a) watt (W) (b) volt (V) (c) ampere (A) (d) ohm (Ω)
37. 37.💡 An LED is joined to a 5 V battery through a 470 Ω resistor; the leg next to the flat edge of its rim goes to the + side. What happens? (a) may burn out (b) lights up (c) does not light
38. 38.💡 A red LED (it uses 2 V) is joined with a 200 Ω resistor to a 5 V supply. What current flows (in mA)?
39. 39.True or false: on an LED, the round-side leg is the cathode (−). (a) True (b) False
40. 40.True or false: a capacitor smooths a wobbly supply. (a) True (b) False

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