Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 30 · 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 0.25 A flows through a 5 Ω resistor. What is the voltage across it (in volts)? =
2. 2.📏 Voltmeter or ammeter: which one is joined across a part? (a) ammeter (b) voltmeter
3. 3.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 280 Ω resistor? (a) grey-red-brown (b) red-grey-brown (c) red-grey-red (d) red-grey-black
4. 4.🔺 A current of 20 mA flows through a 330 Ω resistor. What is the voltage across it (in volts)? =
5. 5.🌈 A resistor has the colour bands blue, white, yellow. What is its value in kilo-ohms (kΩ)? =
6. 6.⚡ A home appliance on the 230 V mains takes 5 A. What is its power (in watts)?
7. 7.🌈 A resistor has the colour bands white, yellow, orange. What is its value (in ohms)?
8. 8.🌈 A resistor has the colour bands brown, brown, black. What is its value (in ohms)?
9. 9.True or false: an LED glows using little power. (a) True (b) False
10. 10.🌈 Which band is read first on a resistor? (a) the widest gap (b) the one nearest an end (c) the gold band (d) any band
11. 11.🔺 A current of 2 A flows through a 15 Ω resistor. What is the voltage across it (in volts)? =
12. 12.🔺 A current of 2.5 A flows when 12.5 V is joined across a resistor. What is its resistance (in ohms)?
13. 13.True or false: on an LED, the leg by the flat edge is the anode (+). (a) True (b) False
14. 14.⚡ An 18 W device works on 6 V. What current does it take (in amperes)? =
15. 15.🔺 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
16. 16.🧾 A family uses 150 units of electricity in a month and each unit costs ₹9. What is the bill (in ₹)?
17. 17.🧮 Adding another resistor in series makes the total resistance … (a) bigger (b) zero (c) stay the same (d) smaller
18. 18.🧩 Which part changes electrical energy into sound? (a) a resistor (b) a buzzer (c) a diode (d) a capacitor
19. 19.True or false: resistance is measured in watts (W). (a) False (b) True
20. 20.🧩 Which component lets current go one way? (a) diode (b) potentiometer (c) motor (d) resistor
21. 21.💡 What does LED stand for? (a) light-emitting diode (b) low energy device (c) light energy dial (d) large electric dial
22. 22.🧮 Three equal 30 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
23. 23.🔺 A current of 0.1 A flows through a 6 Ω resistor. What is the voltage across it (in volts)? =
24. 24.Which of these saves electricity? (a) use old filament bulbs (b) run fans in empty rooms (c) leave the TV on standby (d) switch off empty rooms
25. 25.🧾 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?
26. 26.⚡ A device works on 24 V and takes 2 A. What is its power (in watts)? =
27. 27.🧮 A 1.75 V battery is joined to 3 Ω and 4 Ω resistors in series. What current flows (in amperes)? =
28. 28.What does a thermistor do? (a) smooths a wobbly supply (b) senses how hot it is (c) blows if current is high (d) limits the current
29. 29.Which of these is measured in volts (V)? (a) energy used each second (b) power (c) voltage (d) current
30. 30.📏 How many kilowatts (kW) is 4900 W? =
31. 31.⚡ Which formula gives electric power? (a) P = V × I (b) P = V ÷ I (c) P = I ÷ V (d) P = V + I
32. 32.📏 How many amperes (A) is 240 mA? =
33. 33.🔺 A 10 V supply is joined across a 10 Ω resistor. What current flows (in amperes)? =
34. 34.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) becomes zero (b) gets bigger (c) stays the same (d) gets smaller
35. 35.⚡ A home appliance on the 230 V mains takes 10 A. What is its power (in watts)?
36. 36.🌈 A resistor has the colour bands white, blue, black. What is its value (in ohms)?
37. 37.🌈 In the resistor colour code, which number does black stand for?
38. 38.🔺 A current of 20 mA flows through a 470 Ω resistor. What is the voltage across it (in volts)? =
39. 39.⚡ Power tells us … (a) the size of a cell (b) the colour of light (c) energy used each second (d) the length of a wire
40. 40.True or false: the voltmeter is joined across a part. (a) False (b) True

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