Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 285 · 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.What does a diode do? (a) lets current go one way (b) blows if current is high (c) makes things spin (d) senses how hot it is
2. 2.True or false: the voltmeter measures current. (a) False (b) True
3. 3.🧮 Two resistors in parallel give a total that is … (a) less than either one (b) their sum (c) more than either one (d) always zero
4. 4.⚡ A home appliance on the 230 V mains takes 1.5 A. What is its power (in watts)?
5. 5.⚡ Power tells us … (a) the length of a wire (b) the size of a cell (c) energy used each second (d) the colour of light
6. 6.⚡ Which formula gives electric power? (a) P = I ÷ V (b) P = V × I (c) P = V + I (d) P = V ÷ I
7. 7.📏 Which unit measures the push of a cell? (a) ohm (Ω) (b) ampere (A) (c) volt (V) (d) watt (W)
8. 8.📏 How many milliamperes (mA) make 1 ampere? (a) 10 (b) 100 (c) 60 (d) 1000
9. 9.Which of these saves electricity? (a) leave the TV on standby (b) use old filament bulbs (c) switch off empty rooms (d) iron one shirt at a time
10. 10.🧮 Adding another resistor in series makes the total resistance … (a) bigger (b) zero (c) stay the same (d) smaller
11. 11.💡 Why does an LED need a resistor in series? (a) to store charge (b) to make it brighter (c) to limit the current (d) to change its colour
12. 12.What does a capacitor do? (a) smooths a wobbly supply (b) glows using little power (c) limits the current (d) makes a beeping sound
13. 13.True or false: the ammeter is joined across a part. (a) False (b) True
14. 14.🔺 A current of 2 A flows through a 3 Ω resistor. What is the voltage across it (in volts)? =
15. 15.💡 On an LED, is the shorter leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
16. 16.True or false: to switch off empty rooms saves electricity. (a) True (b) False
17. 17.💡 An LED is joined to a 5 V battery with no resistor; its long leg goes to the + side and its short leg to the − side. What happens? (a) does not light (b) may burn out (c) lights up
18. 18.🧮 Two equal 10 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
19. 19.🔺 A current of 2 A flows when 40 V is joined across a resistor. What is its resistance (in ohms)?
20. 20.Which of these wastes electricity? (a) use LED lamps (b) use daylight to read (c) unplug idle chargers (d) leave the TV on standby
21. 21.🔺 A current of 10 mA flows through a 470 Ω resistor. What is the voltage across it (in volts)? =
22. 22.🔺 A current of 50 mA flows through a 120 Ω resistor. What is the voltage across it (in volts)? =
23. 23.True or false: energy used each second is measured in volts (V). (a) False (b) True
24. 24.🧾 A family uses 130 units of electricity in a month and each unit costs ₹9. What is the bill (in ₹)?
25. 25.🧮 Resistors of 470 Ω, 33 Ω, 47 Ω and 330 Ω are joined in series. What is the total resistance (in ohms)?
26. 26.⚡ A 48 W device works on 24 V. What current does it take (in amperes)? =
27. 27.What does an LDR do? (a) boosts a small signal (b) is a resistance knob (c) turns a fan or wheels (d) senses how bright it is
28. 28.🧾 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
29. 29.🔺 A current of 0.1 A flows when 2 V is joined across a resistor. What is its resistance (in ohms)?
30. 30.🧩 Which component makes things spin? (a) transistor (b) motor (c) LDR (d) buzzer
31. 31.🧩 A capacitor in a circuit can … (a) measure heat (b) spin a wheel (c) store charge briefly (d) make light
32. 32.🌈 Which band is read first on a resistor? (a) the one nearest an end (b) the widest gap (c) the gold band (d) any band
33. 33.🔺 A current of 0.2 A flows through a 20 Ω resistor. What is the voltage across it (in volts)? =
34. 34.🧮 Two equal 40 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
35. 35.True or false: how much a part resists is measured in ohms (Ω). (a) False (b) True
36. 36.🔺 A current of 3 A flows when 18 V is joined across a resistor. What is its resistance (in ohms)?
37. 37.🧮 Resistors of 47 Ω and 330 Ω are joined in series. What is the total resistance (in ohms)?
38. 38.🧮 Two equal 470 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
39. 39.🧮 Four equal 20 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
40. 40.📏 In the water-pipe picture of a circuit, current is like … (a) the pipe colour (b) a narrow pipe (c) the water pressure (d) the flow of water

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