Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 529 · 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.📏 How many kilowatts (kW) is 800 W? =
2. 2.🧾 A family uses 180 units of electricity in a month and each unit costs ₹6. What is the bill (in ₹)?
3. 3.🔍 Which is the odd one out? (a) close the fridge quickly (b) unplug idle chargers (c) leave the TV on standby (d) use LED lamps
4. 4.True or false: on an LED, the leg by the flat edge is the cathode (−). (a) True (b) False
5. 5.⚡ Which formula gives electric power? (a) P = V + I (b) P = V ÷ I (c) P = I ÷ V (d) P = V × I
6. 6.💡 Why does an LED need a resistor in series? (a) to make it brighter (b) to store charge (c) to change its colour (d) to limit the current
7. 7.🔺 A current of 0.2 A flows through a 12 Ω resistor. What is the voltage across it (in volts)? =
8. 8.🌈 Which band is read first on a resistor? (a) the one nearest an end (b) any band (c) the widest gap (d) the gold band
9. 9.📏 In the water-pipe picture of a circuit, current is like … (a) the water pressure (b) the flow of water (c) the pipe colour (d) a narrow pipe
10. 10.🌈 A gold fourth band on a resistor means the value may be off by … (a) 0 % (b) 5 % (c) 50 % (d) 25 %
11. 11.🌈 A resistor has the colour bands brown, red, orange. What is its value in kilo-ohms (kΩ)? =
12. 12.🔺 A current of 40 mA flows through a 100 Ω resistor. What is the voltage across it (in volts)? =
13. 13.🔺 A 15 V supply is joined across a 5 Ω resistor. What current flows (in amperes)? =
14. 14.💡 What does LED stand for? (a) large electric dial (b) low energy device (c) light energy dial (d) light-emitting diode
15. 15.💡 An LED is joined to a 3 V battery through a 220 Ω resistor; its long leg goes to the + side and its short leg to the − side. What happens? (a) lights up (b) does not light (c) may burn out
16. 16.🔺 In the V-I-R triangle, how do we find V? (a) V = I × R (b) V = I ÷ R (c) V = I + R (d) V = R ÷ I
17. 17.🧩 Which part changes electrical energy into sound? (a) a diode (b) a buzzer (c) a capacitor (d) a resistor
18. 18.🧩 Which component smooths a wobbly supply? (a) transistor (b) capacitor (c) motor (d) potentiometer
19. 19.🔺 A current of 20 mA flows through a 330 Ω resistor. What is the voltage across it (in volts)? =
20. 20.🔺 A current of 1 A flows when 6 V is joined across a resistor. What is its resistance (in ohms)?
21. 21.🔺 A 22.5 V supply is joined across a 15 Ω resistor. What current flows (in amperes)? =
22. 22.🧩 Which component glows using little power? (a) potentiometer (b) LED (c) LDR (d) motor
23. 23.📏 Voltmeter or ammeter: which one is joined in series? (a) ammeter (b) voltmeter
24. 24.🔍 Which is the odd one out? (a) unplug idle chargers (b) switch off empty rooms (c) close the fridge quickly (d) leave fridge door open
25. 25.Which of these saves electricity? (a) leave fridge door open (b) set the AC to 24 °C (c) run fans in empty rooms (d) leave the TV on standby
26. 26.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) gets smaller (b) becomes zero (c) stays the same (d) gets bigger
27. 27.🔺 In the V-I-R triangle, how do we find R? (a) R = V ÷ I (b) R = V × I (c) R = I ÷ V (d) R = V + I
28. 28.⚡ A device works on 1.5 V and takes 0.25 A. What is its power (in watts)? =
29. 29.🌈 A resistor has the colour bands yellow, yellow, orange. What is its value in kilo-ohms (kΩ)? =
30. 30.True or false: to use LED lamps saves electricity. (a) False (b) True
31. 31.⚡ A 2.25 W device works on 1.5 V. What current does it take (in amperes)? =
32. 32.⚡ 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
33. 33.🧮 Resistors of 150 Ω, 150 Ω and 20 Ω are joined in series. What is the total resistance (in ohms)?
34. 34.📏 Voltmeter or ammeter: which one measures current? (a) ammeter (b) voltmeter
35. 35.🌈 A resistor has the colour bands orange, red, red. What is its value in kilo-ohms (kΩ)? =
36. 36.🧮 A 100 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)?
37. 37.🧾 One “unit” on an electricity bill is … (a) 1 watt (b) 1 kilowatt-hour (kWh) (c) 1 volt (d) 1 ampere
38. 38.🧮 Adding another resistor in series makes the total resistance … (a) smaller (b) stay the same (c) zero (d) bigger
39. 39.🔺 A current of 20 mA flows when 3 V is joined across a resistor. What is its resistance (in ohms)?
40. 40.🔺 A current of 0.1 A flows when 1 V is joined across a resistor. What is its resistance (in ohms)?

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