Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 904 · 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 gold fourth band on a resistor means the value may be off by … (a) 0 % (b) 50 % (c) 5 % (d) 25 %
2. 2.🔍 Which is the odd one out? (a) leave the TV on standby (b) use LED lamps (c) use daylight to read (d) set the AC to 24 °C
3. 3.Which of these is measured in ohms (Ω)? (a) the push of a cell (b) how much a part resists (c) the flow of charge (d) voltage
4. 4.💡 On an LED, is the longer leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
5. 5.📏 How many ohms make 1 kilo-ohm (kΩ)? (a) 100 (b) 10 (c) 1000 (d) 1024
6. 6.🧩 A capacitor in a circuit can … (a) measure heat (b) store charge briefly (c) spin a wheel (d) make light
7. 7.⚡ A device works on 5 V and takes 1.5 A. What is its power (in watts)? =
8. 8.🌈 In the resistor colour code, which number does orange stand for?
9. 9.True or false: on an LED, the round-side leg is the cathode (−). (a) False (b) True
10. 10.🧾 A family uses 40 units of electricity in a month and each unit costs ₹5. What is the bill (in ₹)?
11. 11.True or false: a transistor smooths a wobbly supply. (a) False (b) True
12. 12.🔺 A current of 20 mA flows when 10 V is joined across a resistor. What is its resistance (in ohms)?
13. 13.💡 What happens if an LED is put in backwards? (a) it makes a sound (b) it does not light (c) it changes colour (d) it lights brighter
14. 14.🔺 A current of 0.5 A flows through a 6 Ω resistor. What is the voltage across it (in volts)? =
15. 15.True or false: to leave fridge door open saves electricity. (a) False (b) True
16. 16.🧮 Two resistors in parallel give a total that is … (a) more than either one (b) always zero (c) their sum (d) less than either one
17. 17.⚡ A 2.4 W device works on 12 V. What current does it take (in amperes)? =
18. 18.🌈 In the resistor colour code, which number does yellow stand for?
19. 19.🔍 Which is the odd one out? (a) unplug idle chargers (b) set the AC to 24 °C (c) leave fridge door open (d) switch off empty rooms
20. 20.🔺 A current of 25 mA flows when 2.5 V is joined across a resistor. What is its resistance (in ohms)?
21. 21.Which of these saves electricity? (a) use LED lamps (b) iron one shirt at a time (c) run fans in empty rooms (d) leave the TV on standby
22. 22.🧾 Which lamp gives the same light for the least power? (a) an LED lamp (b) a candle (c) an oil lamp (d) a filament bulb
23. 23.What does a fuse do? (a) boosts a small signal (b) is a resistance knob (c) blows if current is high (d) limits the current
24. 24.🧮 A 2.25 V battery is joined to 3 Ω and 6 Ω resistors in series. What current flows (in amperes)? =
25. 25.🧮 A 20 Ω resistor is joined in series with two equal 1000 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
26. 26.🧮 Resistors of 68 Ω and 50 Ω are joined in series. What is the total resistance (in ohms)?
27. 27.True or false: on an LED, the longer leg is the cathode (−). (a) False (b) True
28. 28.🔺 A 6 V supply is joined across a 12 Ω resistor. What current flows (in amperes)? =
29. 29.📏 Voltmeter or ammeter: which one measures voltage? (a) voltmeter (b) ammeter
30. 30.Which of these saves electricity? (a) switch off empty rooms (b) run fans in empty rooms (c) use old filament bulbs (d) leave fridge door open
31. 31.🧩 Which component glows using little power? (a) LDR (b) transistor (c) buzzer (d) LED
32. 32.📏 Which unit measures resistance? (a) ohm (Ω) (b) volt (V) (c) watt (W) (d) ampere (A)
33. 33.🌈 A resistor has the colour bands blue, brown, red. What is its value (in ohms)?
34. 34.🧾 A 1500 W appliance runs for 4 hours. How many units (kWh) of electricity does it use? =
35. 35.📏 How many watts (W) is 3.5 kW?
36. 36.Which of these is measured in volts (V)? (a) current (b) resistance (c) the push of a cell (d) energy used each second
37. 37.📏 How many kilowatts (kW) is 650 W? =
38. 38.🔺 A current of 50 mA flows through a 250 Ω resistor. What is the voltage across it (in volts)? =
39. 39.🧩 Which part changes electrical energy into movement? (a) a motor (b) an LED (c) a resistor (d) a fuse
40. 40.🔺 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

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