Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 465 · 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 20 mA flows when 2.4 V is joined across a resistor. What is its resistance (in ohms)?
2. 2.🧾 A family uses 190 units of electricity in a month and each unit costs ₹5. What is the bill (in ₹)?
3. 3.🔺 A 0.2 V supply is joined across a 2 Ω resistor. What current flows (in amperes)? =
4. 4.💡 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?
5. 5.📏 Which unit measures resistance? (a) watt (W) (b) ampere (A) (c) volt (V) (d) ohm (Ω)
6. 6.🌈 A resistor has the colour bands orange, red, orange. What is its value (in ohms)?
7. 7.🧮 A 470 Ω resistor is joined in series with two equal 10 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
8. 8.🔺 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
9. 9.True or false: on an LED, the leg by the flat edge is the cathode (−). (a) False (b) True
10. 10.True or false: the ammeter measures current. (a) False (b) True
11. 11.💡 Does it save or waste electricity to use old filament bulbs? (a) saves electricity (b) wastes electricity
12. 12.🔺 A 6.25 V supply is joined across a 250 Ω resistor. What current flows (in milliamperes, mA)?
13. 13.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) gets smaller (b) becomes zero (c) gets bigger (d) stays the same
14. 14.🔺 A current of 10 mA flows through a 120 Ω resistor. What is the voltage across it (in volts)? =
15. 15.⚡ A home appliance on the 230 V mains takes 1 A. What is its power (in watts)?
16. 16.🔺 A current of 40 mA flows when 16 V is joined across a resistor. What is its resistance (in ohms)?
17. 17.True or false: the ammeter is joined across a part. (a) True (b) False
18. 18.📏 How many milliamperes (mA) is 1.79 A?
19. 19.🧩 A capacitor in a circuit can … (a) measure heat (b) make light (c) spin a wheel (d) store charge briefly
20. 20.💡 What does LED stand for? (a) large electric dial (b) light-emitting diode (c) light energy dial (d) low energy device
21. 21.⚡ Which formula gives electric power? (a) P = V ÷ I (b) P = I ÷ V (c) P = V × I (d) P = V + I
22. 22.🔺 A current of 0.1 A flows through a 10 Ω resistor. What is the voltage across it (in volts)? =
23. 23.🧮 Two equal 40 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
24. 24.🔺 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
25. 25.🔺 A current of 2 A flows when 10 V is joined across a resistor. What is its resistance (in ohms)?
26. 26.🧮 A 150 Ω resistor is joined in series with two equal 330 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
27. 27.🧩 Which part changes electrical energy into sound? (a) a capacitor (b) a diode (c) a buzzer (d) a resistor
28. 28.🧮 A 3.2 V battery is joined to 6 Ω and 10 Ω resistors in series. What current flows (in amperes)? =
29. 29.🌈 A resistor has the colour bands blue, green, red. What is its value in kilo-ohms (kΩ)? =
30. 30.🧾 One “unit” on an electricity bill is … (a) 1 kilowatt-hour (kWh) (b) 1 volt (c) 1 watt (d) 1 ampere
31. 31.What does a transistor do? (a) smooths a wobbly supply (b) turns a fan or wheels (c) boosts a small signal (d) limits the current
32. 32.What does a fuse do? (a) turns a fan or wheels (b) has coloured bands (c) blows if current is high (d) stores a little charge
33. 33.⚡ Power tells us … (a) the length of a wire (b) energy used each second (c) the colour of light (d) the size of a cell
34. 34.Which of these is measured in amperes (A)? (a) energy used each second (b) voltage (c) how much a part resists (d) current
35. 35.🌈 A gold fourth band on a resistor means the value may be off by … (a) 50 % (b) 0 % (c) 25 % (d) 5 %
36. 36.🌈 In the resistor colour code, which number does black stand for?
37. 37.🧾 A 100 W filament bulb is swapped for a 15 W LED lamp that gives about the same light. Both would run for 10 hours. How many watt-hours (Wh) are saved?
38. 38.🔺 A current of 2.5 A flows through a 20 Ω resistor. What is the voltage across it (in volts)? =
39. 39.What does a capacitor do? (a) limits the current (b) beeps for an alarm (c) smooths a wobbly supply (d) has coloured bands
40. 40.🧮 Two equal 220 Ω resistors are joined in parallel. What is the total resistance (in ohms)?

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