Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 248 · 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.⚡ A 24 W device works on 24 V. What current does it take (in amperes)? =
2. 2.🔺 In the V-I-R triangle, how do we find I? (a) I = V + R (b) I = R ÷ V (c) I = V ÷ R (d) I = V × R
3. 3.🌈 In the resistor colour code, which number does red stand for?
4. 4.📏 Which unit measures the flow of charge? (a) volt (V) (b) watt (W) (c) ampere (A) (d) ohm (Ω)
5. 5.📏 How many milliamperes (mA) is 0.45 A?
6. 6.💡 A red LED uses 2 V and should get 25 mA. It runs from a 6 V supply. What resistor (in ohms) is needed in series?
7. 7.💡 What does LED stand for? (a) large electric dial (b) light energy dial (c) light-emitting diode (d) low energy device
8. 8.⚡ A device works on 24 V and takes 0.5 A. What is its power (in watts)? =
9. 9.🧮 Adding another resistor in series makes the total resistance … (a) zero (b) smaller (c) stay the same (d) bigger
10. 10.🌈 A resistor has the colour bands white, blue, black. What is its value (in ohms)?
11. 11.🧾 A family uses 120 units of electricity in a month and each unit costs ₹7. What is the bill (in ₹)?
12. 12.📏 Voltmeter or ammeter: which one measures voltage? (a) ammeter (b) voltmeter
13. 13.🔍 Which is the odd one out? (a) use LED lamps (b) unplug idle chargers (c) close the fridge quickly (d) leave the TV on standby
14. 14.🧩 Which component lets current go one way? (a) diode (b) LDR (c) transistor (d) fuse
15. 15.🧮 A 1.6 V battery is joined to 4 Ω and 4 Ω resistors in series. What current flows (in amperes)? =
16. 16.🧮 Two equal 50 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
17. 17.💡 An LED is joined to a 3 V battery through a 220 Ω resistor; its long leg goes to the + side and its short leg to the − side. What happens? (a) lights up (b) may burn out (c) does not light
18. 18.🧾 One “unit” on an electricity bill is … (a) 1 ampere (b) 1 volt (c) 1 kilowatt-hour (kWh) (d) 1 watt
19. 19.🌈 A gold fourth band on a resistor means the value may be off by … (a) 0 % (b) 50 % (c) 25 % (d) 5 %
20. 20.📏 Voltmeter or ammeter: which one is joined across a part? (a) voltmeter (b) ammeter
21. 21.⚡ A device works on 6 V and takes 1 A. What is its power (in watts)? =
22. 22.🔺 A current of 40 mA flows when 16 V is joined across a resistor. What is its resistance (in ohms)?
23. 23.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) gets bigger (b) gets smaller (c) stays the same (d) becomes zero
24. 24.🌈 A resistor has the colour bands red, brown, red. What is its value (in ohms)?
25. 25.True or false: a transistor boosts a small signal. (a) False (b) True
26. 26.📏 In the water-pipe picture of a circuit, resistance is like … (a) a narrow pipe (b) a bigger tank (c) the water pressure (d) the flow of water
27. 27.🌈 Which band is read first on a resistor? (a) the gold band (b) the one nearest an end (c) any band (d) the widest gap
28. 28.🌈 A resistor has the colour bands orange, blue, orange. What is its value (in ohms)?
29. 29.🧮 A 2 V battery is joined to 10 Ω and 10 Ω resistors in series. What current flows (in amperes)? =
30. 30.True or false: energy used each second is measured in ohms (Ω). (a) False (b) True
31. 31.True or false: the flow of charge is measured in amperes (A). (a) False (b) True
32. 32.True or false: the ammeter is joined across a part. (a) False (b) True
33. 33.🌈 A resistor has the colour bands violet, green, brown. What is its value (in ohms)?
34. 34.True or false: a fuse blows if current is high. (a) False (b) True
35. 35.💡 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) lights up (b) may burn out (c) does not light
36. 36.⚡ A device works on 3 V and takes 2 A. What is its power (in watts)? =
37. 37.🔺 A current of 40 mA flows through a 220 Ω resistor. What is the voltage across it (in volts)? =
38. 38.🔺 A current of 1.5 A flows through a 6 Ω resistor. What is the voltage across it (in volts)? =
39. 39.🧩 Which part changes electrical energy into movement? (a) a motor (b) an LED (c) a fuse (d) a resistor
40. 40.🔍 Which is the odd one out? (a) leave fridge door open (b) run fans in empty rooms (c) leave the TV on standby (d) switch off empty rooms

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