Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 557 · 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 current of 50 mA flows through a 470 Ω resistor. What is the voltage across it (in volts)? =
2. 2.True or false: on an LED, the shorter leg is the cathode (−). (a) False (b) True
3. 3.🧾 One “unit” on an electricity bill is … (a) 1 ampere (b) 1 volt (c) 1 watt (d) 1 kilowatt-hour (kWh)
4. 4.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 77 Ω resistor? (a) grey-violet-black (b) violet-violet-brown (c) violet-violet-black (d) violet-grey-black
5. 5.📏 How many amperes (A) is 2130 mA? =
6. 6.🧮 Adding another resistor in series makes the total resistance … (a) smaller (b) stay the same (c) zero (d) bigger
7. 7.📏 Voltmeter or ammeter: which one measures voltage? (a) ammeter (b) voltmeter
8. 8.🧩 Which component glows using little power? (a) transistor (b) capacitor (c) resistor (d) LED
9. 9.🌈 A gold fourth band on a resistor means the value may be off by … (a) 25 % (b) 0 % (c) 50 % (d) 5 %
10. 10.🧾 A 200 W appliance runs for 2 hours. How many units (kWh) of electricity does it use? =
11. 11.⚡ A 36 W device works on 12 V. What current does it take (in amperes)? =
12. 12.True or false: to unplug idle chargers wastes electricity. (a) False (b) True
13. 13.📏 Voltmeter or ammeter: which one is joined in series? (a) ammeter (b) voltmeter
14. 14.Which of these is measured in volts (V)? (a) voltage (b) current (c) resistance (d) energy used each second
15. 15.🔺 A current of 2.5 A flows through an 8 Ω resistor. What is the voltage across it (in volts)? =
16. 16.🔺 A current of 0.25 A flows when 1.5 V is joined across a resistor. What is its resistance (in ohms)?
17. 17.🌈 In the resistor colour code, which number does grey stand for?
18. 18.🔺 A current of 0.25 A flows through a 2 Ω resistor. What is the voltage across it (in volts)? =
19. 19.🌈 In the resistor colour code, which number does red stand for?
20. 20.🔺 In the V-I-R triangle, how do we find V? (a) V = I ÷ R (b) V = R ÷ I (c) V = I × R (d) V = I + R
21. 21.🔺 A current of 20 mA flows when 4.4 V is joined across a resistor. What is its resistance (in ohms)?
22. 22.🔺 A 2.5 V supply is joined across a 5 Ω resistor. What current flows (in amperes)? =
23. 23.🌈 In the resistor colour code, which number does black stand for?
24. 24.🌈 A resistor has the colour bands blue, violet, orange. What is its value (in ohms)?
25. 25.💡 A blue LED uses 3 V and should get 20 mA. It runs from a 9 V supply. What resistor (in ohms) is needed in series?
26. 26.True or false: an LDR makes a beeping sound. (a) False (b) True
27. 27.True or false: to use LED lamps wastes electricity. (a) True (b) False
28. 28.🧾 A family uses 180 units of electricity in a month and each unit costs ₹6. What is the bill (in ₹)?
29. 29.🔺 A current of 1.5 A flows through an 8 Ω resistor. What is the voltage across it (in volts)? =
30. 30.🧾 A family uses 160 units of electricity in a month and each unit costs ₹4. What is the bill (in ₹)?
31. 31.🔺 A current of 0.1 A flows through a 4 Ω resistor. What is the voltage across it (in volts)? =
32. 32.🔺 A 0.4 V supply is joined across a 2 Ω resistor. What current flows (in amperes)? =
33. 33.📏 In the water-pipe picture of a circuit, resistance is like … (a) a narrow pipe (b) a bigger tank (c) the flow of water (d) the water pressure
34. 34.⚡ Power tells us … (a) energy used each second (b) the size of a cell (c) the colour of light (d) the length of a wire
35. 35.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark an 86000 Ω resistor? (a) grey-blue-red (b) blue-grey-orange (c) grey-blue-yellow (d) grey-blue-orange
36. 36.🧾 A family uses 200 units of electricity in a month and each unit costs ₹7. What is the bill (in ₹)?
37. 37.🔺 A 4 V supply is joined across a 200 Ω resistor. What current flows (in milliamperes, mA)?
38. 38.⚡ A device works on 3 V and takes 0.5 A. What is its power (in watts)? =
39. 39.💡 Does it save or waste electricity to use daylight to read? (a) saves electricity (b) wastes electricity
40. 40.💡 An LED is joined to a 6 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) lights up (c) may burn out

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