Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 459 · 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 LED stand for? (a) low energy device (b) large electric dial (c) light energy dial (d) light-emitting diode
2. 2.True or false: on an LED, the round-side leg is the anode (+). (a) False (b) True
3. 3.🌈 In the resistor colour code, which number does violet stand for?
4. 4.Which of these saves electricity? (a) use old filament bulbs (b) leave the TV on standby (c) iron one shirt at a time (d) close the fridge quickly
5. 5.🧮 Adding another resistor in series makes the total resistance … (a) bigger (b) stay the same (c) zero (d) smaller
6. 6.Which of these is measured in amperes (A)? (a) the push of a cell (b) current (c) resistance (d) how much a part resists
7. 7.Which of these is measured in watts (W)? (a) power (b) resistance (c) current (d) voltage
8. 8.Which of these saves electricity? (a) iron one shirt at a time (b) switch off empty rooms (c) leave fridge door open (d) run fans in empty rooms
9. 9.🧮 Three equal 30 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
10. 10.⚡ A home appliance on the 230 V mains takes 1 A. What is its power (in watts)?
11. 11.🧩 Which component senses how hot it is? (a) buzzer (b) LED (c) LDR (d) thermistor
12. 12.⚡ Which formula gives electric power? (a) P = I ÷ V (b) P = V + I (c) P = V ÷ I (d) P = V × I
13. 13.🔺 A current of 50 mA flows when 12.5 V is joined across a resistor. What is its resistance (in ohms)?
14. 14.🧩 Which component lets current go one way? (a) fuse (b) diode (c) LDR (d) potentiometer
15. 15.💡 On an LED, is the shorter leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
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.💡 A red LED (it uses 2 V) is joined with a 300 Ω resistor to an 8 V supply. What current flows (in mA)?
18. 18.💡 On an LED, is the longer leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
19. 19.📏 In the water-pipe picture of a circuit, resistance is like … (a) a bigger tank (b) the water pressure (c) a narrow pipe (d) the flow of water
20. 20.True or false: power is measured in watts (W). (a) False (b) True
21. 21.🧮 Three equal 75 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
22. 22.💡 Does it save or waste electricity to set the AC to 24 °C? (a) wastes electricity (b) saves electricity
23. 23.🌈 Which band is read first on a resistor? (a) the widest gap (b) any band (c) the one nearest an end (d) the gold band
24. 24.🧩 Which component makes things spin? (a) potentiometer (b) LED (c) capacitor (d) motor
25. 25.True or false: on an LED, the leg by the flat edge is the cathode (−). (a) True (b) False
26. 26.🧩 Which component smooths a wobbly supply? (a) capacitor (b) fuse (c) resistor (d) potentiometer
27. 27.🔺 A current of 1 A flows when 10 V is joined across a resistor. What is its resistance (in ohms)?
28. 28.🔺 In the V-I-R triangle, how do we find I? (a) I = V × R (b) I = V + R (c) I = V ÷ R (d) I = R ÷ V
29. 29.🧮 Two equal 330 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
30. 30.🧮 A 68 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)?
31. 31.True or false: the voltmeter measures current. (a) True (b) False
32. 32.🌈 In the resistor colour code, which number does blue stand for?
33. 33.🧩 Which part changes electrical energy into movement? (a) a resistor (b) a fuse (c) an LED (d) a motor
34. 34.True or false: to use LED lamps wastes electricity. (a) True (b) False
35. 35.🔺 A current of 50 mA flows through a 100 Ω resistor. What is the voltage across it (in volts)? =
36. 36.True or false: the voltmeter is joined in series. (a) False (b) True
37. 37.📏 How many watts (W) is 1.2 kW?
38. 38.🔺 A current of 0.1 A flows through a 4 Ω resistor. What is the voltage across it (in volts)? =
39. 39.🧾 A family uses 150 units of electricity in a month and each unit costs ₹8. What is the bill (in ₹)?
40. 40.🔺 A current of 0.1 A flows through a 2 Ω resistor. What is the voltage across it (in volts)? =

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