Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 995 · 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 0.1 A flows through a 6 Ω resistor. What is the voltage across it (in volts)? =
2. 2.🧾 A family uses 60 units of electricity in a month and each unit costs ₹4. What is the bill (in ₹)?
3. 3.True or false: a buzzer beeps for an alarm. (a) False (b) True
4. 4.💡 What happens if an LED is put in backwards? (a) it makes a sound (b) it changes colour (c) it lights brighter (d) it does not light
5. 5.📏 Voltmeter or ammeter: which one measures voltage? (a) voltmeter (b) ammeter
6. 6.📏 In the water-pipe picture of a circuit, resistance is like … (a) the water pressure (b) the flow of water (c) a bigger tank (d) a narrow pipe
7. 7.📏 How many milliamperes (mA) is 2.25 A?
8. 8.Which of these is measured in ohms (Ω)? (a) the flow of charge (b) resistance (c) voltage (d) current
9. 9.🧮 Two equal 100 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
10. 10.🔺 A 3.75 V supply is joined across a 150 Ω resistor. What current flows (in milliamperes, mA)?
11. 11.🔺 A current of 20 mA flows when 5 V is joined across a resistor. What is its resistance (in ohms)?
12. 12.🔺 In the V-I-R triangle, how do we find I? (a) I = R ÷ V (b) I = V × R (c) I = V + R (d) I = V ÷ R
13. 13.🔺 In the V-I-R triangle, how do we find V? (a) V = I + R (b) V = I ÷ R (c) V = R ÷ I (d) V = I × R
14. 14.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 54 Ω resistor? (a) blue-yellow-black (b) green-yellow-brown (c) green-yellow-black (d) yellow-green-black
15. 15.📏 How many watts (W) is 2.3 kW?
16. 16.🌈 A gold fourth band on a resistor means the value may be off by … (a) 5 % (b) 0 % (c) 50 % (d) 25 %
17. 17.🌈 A resistor has the colour bands violet, green, red. What is its value (in ohms)?
18. 18.⚡ A 12 W device works on 6 V. What current does it take (in amperes)? =
19. 19.True or false: on an LED, the leg by the flat edge is the cathode (−). (a) True (b) False
20. 20.🧾 A 60 W filament bulb is swapped for a 9 W LED lamp that gives about the same light. Both would run for 2 hours. How many watt-hours (Wh) are saved?
21. 21.⚡ Power tells us … (a) the colour of light (b) the length of a wire (c) energy used each second (d) the size of a cell
22. 22.🔺 A 30 V supply is joined across a 20 Ω resistor. What current flows (in amperes)? =
23. 23.🔺 A current of 0.2 A flows when 0.6 V is joined across a resistor. What is its resistance (in ohms)?
24. 24.💡 On an LED, is the shorter leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
25. 25.🔺 A 1 V supply is joined across a 10 Ω resistor. What current flows (in amperes)? =
26. 26.Which of these saves electricity? (a) iron one shirt at a time (b) use old filament bulbs (c) run fans in empty rooms (d) switch off empty rooms
27. 27.True or false: on an LED, the leg by the flat edge is the anode (+). (a) False (b) True
28. 28.🔺 A current of 25 mA flows through a 400 Ω resistor. What is the voltage across it (in volts)? =
29. 29.🔺 A current of 40 mA flows when 18.8 V is joined across a resistor. What is its resistance (in ohms)?
30. 30.🔺 A 6.25 V supply is joined across a 250 Ω resistor. What current flows (in milliamperes, mA)?
31. 31.🔺 A 1.25 V supply is joined across a 5 Ω resistor. What current flows (in amperes)? =
32. 32.💡 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?
33. 33.💡 A red LED uses 2 V and should get 25 mA. It runs from a 5 V supply. What resistor (in ohms) is needed in series?
34. 34.⚡ A device works on 1.5 V and takes 0.1 A. What is its power (in watts)? =
35. 35.True or false: energy used each second is measured in watts (W). (a) False (b) True
36. 36.True or false: a motor turns a fan or wheels. (a) True (b) False
37. 37.🧮 Resistors of 470 Ω and 33 Ω are joined in series. What is the total resistance (in ohms)?
38. 38.🧾 A 250 W appliance runs for 10 hours. How many units (kWh) of electricity does it use? =
39. 39.🔺 A current of 2.5 A flows through a 15 Ω resistor. What is the voltage across it (in volts)? =
40. 40.🧮 Resistors of 470 Ω, 20 Ω, 100 Ω and 330 Ω are joined in series. What is the total resistance (in ohms)?

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