Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 816 · 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.💡 On an LED, is the longer leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
2. 2.🔺 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
3. 3.🌈 A gold fourth band on a resistor means the value may be off by … (a) 0 % (b) 25 % (c) 50 % (d) 5 %
4. 4.True or false: how much a part resists is measured in volts (V). (a) True (b) False
5. 5.💡 A red LED (it uses 2 V) is joined with a 100 Ω resistor to a 3 V supply. What current flows (in mA)?
6. 6.🧮 Two equal 100 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
7. 7.💡 Does it save or waste electricity to unplug idle chargers? (a) saves electricity (b) wastes electricity
8. 8.🔺 A 12 V supply is joined across a 300 Ω resistor. What current flows (in milliamperes, mA)?
9. 9.⚡ A 0.6 W device works on 6 V. What current does it take (in amperes)? =
10. 10.🔺 A current of 25 mA flows through a 300 Ω resistor. What is the voltage across it (in volts)? =
11. 11.🧮 Two equal 20 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
12. 12.⚡ Which formula gives electric power? (a) P = V × I (b) P = V + I (c) P = I ÷ V (d) P = V ÷ I
13. 13.🧾 A 100 W filament bulb is swapped for a 15 W LED lamp that gives about the same light. Both would run for 2 hours. How many watt-hours (Wh) are saved?
14. 14.🧮 Resistors of 150 Ω and 10 Ω are joined in series. What is the total resistance (in ohms)?
15. 15.🔺 A current of 20 mA flows through a 220 Ω resistor. What is the voltage across it (in volts)? =
16. 16.🔺 A current of 2 A flows through a 20 Ω resistor. What is the voltage across it (in volts)? =
17. 17.⚡ A device works on 12 V and takes 0.1 A. What is its power (in watts)? =
18. 18.🌈 A resistor has the colour bands brown, violet, yellow. What is its value in kilo-ohms (kΩ)? =
19. 19.🔺 In the V-I-R triangle, how do we find R? (a) R = I ÷ V (b) R = V ÷ I (c) R = V + I (d) R = V × I
20. 20.🧩 Which part changes electrical energy into movement? (a) an LED (b) a fuse (c) a resistor (d) a motor
21. 21.True or false: on an LED, the longer leg is the cathode (−). (a) False (b) True
22. 22.What does a capacitor do? (a) makes a beeping sound (b) smooths a wobbly supply (c) is a resistance knob (d) blows if current is high
23. 23.🌈 A resistor has the colour bands white, violet, red. What is its value in kilo-ohms (kΩ)? =
24. 24.🧾 A family uses 200 units of electricity in a month and each unit costs ₹4. What is the bill (in ₹)?
25. 25.📏 Which unit measures voltage? (a) ohm (Ω) (b) volt (V) (c) watt (W) (d) ampere (A)
26. 26.🔺 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
27. 27.🧾 A family uses 50 units of electricity in a month and each unit costs ₹8. What is the bill (in ₹)?
28. 28.True or false: on an LED, the shorter leg is the anode (+). (a) True (b) False
29. 29.Which of these is measured in volts (V)? (a) power (b) how much a part resists (c) energy used each second (d) voltage
30. 30.🧩 A capacitor in a circuit can … (a) spin a wheel (b) make light (c) measure heat (d) store charge briefly
31. 31.🌈 Which band is read first on a resistor? (a) the gold band (b) the widest gap (c) any band (d) the one nearest an end
32. 32.True or false: the voltmeter measures current. (a) False (b) True
33. 33.🧾 A 100 W filament bulb is swapped for a 15 W LED lamp that gives about the same light. Both would run for 9 hours. How many watt-hours (Wh) are saved?
34. 34.💡 What does LED stand for? (a) low energy device (b) large electric dial (c) light energy dial (d) light-emitting diode
35. 35.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 30 Ω resistor? (a) yellow-black-black (b) yellow-orange-black (c) orange-black-brown (d) orange-black-black
36. 36.📏 How many ohms (Ω) is 5.1 kΩ?
37. 37.🧾 One “unit” on an electricity bill is … (a) 1 watt (b) 1 volt (c) 1 ampere (d) 1 kilowatt-hour (kWh)
38. 38.🔺 A current of 0.25 A flows through a 15 Ω resistor. What is the voltage across it (in volts)? =
39. 39.⚡ A 4.8 W device works on 24 V. What current does it take (in amperes)? =
40. 40.True or false: energy used each second is measured in ohms (Ω). (a) False (b) True

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