Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 840 · 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 lamp gives the same light for the least power? (a) an oil lamp (b) an LED lamp (c) a candle (d) a filament bulb
2. 2.🌈 A resistor has the colour bands violet, red, black. What is its value (in ohms)?
3. 3.🧩 Which component smooths a wobbly supply? (a) resistor (b) LED (c) capacitor (d) thermistor
4. 4.🔺 A 2 V supply is joined across a 100 Ω resistor. What current flows (in milliamperes, mA)?
5. 5.🧾 A family uses 140 units of electricity in a month and each unit costs ₹4. What is the bill (in ₹)?
6. 6.Which of these wastes electricity? (a) leave fridge door open (b) set the AC to 24 °C (c) close the fridge quickly (d) use LED lamps
7. 7.🔺 A current of 0.5 A flows when 7.5 V is joined across a resistor. What is its resistance (in ohms)?
8. 8.True or false: the push of a cell is measured in volts (V). (a) True (b) False
9. 9.🧩 Which component lets current go one way? (a) transistor (b) thermistor (c) resistor (d) diode
10. 10.💡 On an LED, is the leg by the flat edge the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
11. 11.🔺 A current of 50 mA flows through a 120 Ω resistor. What is the voltage across it (in volts)? =
12. 12.📏 In the water-pipe picture of a circuit, current is like … (a) the water pressure (b) a narrow pipe (c) the flow of water (d) the pipe colour
13. 13.🧮 Resistors of 10 Ω, 10 Ω and 50 Ω are joined in series. What is the total resistance (in ohms)?
14. 14.🧩 A capacitor in a circuit can … (a) store charge briefly (b) make light (c) spin a wheel (d) measure heat
15. 15.Which of these wastes electricity? (a) switch off empty rooms (b) use LED lamps (c) set the AC to 24 °C (d) leave the TV on standby
16. 16.🧮 Two resistors in parallel give a total that is … (a) their sum (b) more than either one (c) always zero (d) less than either one
17. 17.🔺 An 8 V supply is joined across a 200 Ω resistor. What current flows (in milliamperes, mA)?
18. 18.Which of these saves electricity? (a) leave fridge door open (b) iron one shirt at a time (c) switch off empty rooms (d) leave the TV on standby
19. 19.⚡ Which formula gives electric power? (a) P = I ÷ V (b) P = V ÷ I (c) P = V + I (d) P = V × I
20. 20.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 630 Ω resistor? (a) blue-orange-red (b) orange-blue-brown (c) blue-orange-brown (d) blue-orange-black
21. 21.📏 In the water-pipe picture of a circuit, resistance is like … (a) a bigger tank (b) the flow of water (c) a narrow pipe (d) the water pressure
22. 22.💡 An LED is joined to a 3 V battery through a 470 Ω resistor; its long leg goes to the − side and its short leg to the + side. What happens? (a) may burn out (b) lights up (c) does not light
23. 23.🔺 A current of 1 A flows when 2 V is joined across a resistor. What is its resistance (in ohms)?
24. 24.🌈 In the resistor colour code, which number does red stand for?
25. 25.📏 In the water-pipe picture of a circuit, voltage is like … (a) the pipe colour (b) the tap handle (c) the water tank lid (d) the water pressure
26. 26.🌈 Which band is read first on a resistor? (a) any band (b) the one nearest an end (c) the widest gap (d) the gold band
27. 27.Which of these saves electricity? (a) iron one shirt at a time (b) close the fridge quickly (c) use old filament bulbs (d) leave fridge door open
28. 28.📏 Voltmeter or ammeter: which one measures current? (a) ammeter (b) voltmeter
29. 29.🔺 A current of 2 A flows through a 10 Ω resistor. What is the voltage across it (in volts)? =
30. 30.True or false: power is measured in watts (W). (a) True (b) False
31. 31.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) becomes zero (b) gets bigger (c) stays the same (d) gets smaller
32. 32.What does a resistor do? (a) limits the current (b) smooths a wobbly supply (c) makes a beeping sound (d) stores a little charge
33. 33.True or false: the voltmeter is joined in series. (a) True (b) False
34. 34.💡 A blue LED uses 3 V and should get 10 mA. It runs from a 12 V supply. What resistor (in ohms) is needed in series?
35. 35.⚡ A device works on 6 V and takes 0.5 A. What is its power (in watts)? =
36. 36.🌈 A gold fourth band on a resistor means the value may be off by … (a) 50 % (b) 0 % (c) 25 % (d) 5 %
37. 37.🔺 A current of 40 mA flows when 20 V is joined across a resistor. What is its resistance (in ohms)?
38. 38.🧾 A family uses 120 units of electricity in a month and each unit costs ₹4. What is the bill (in ₹)?
39. 39.True or false: a transistor boosts a small signal. (a) False (b) True
40. 40.💡 Does it save or waste electricity to switch off empty rooms? (a) saves electricity (b) wastes electricity

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