Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 382 · 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 capacitor in a circuit can … (a) make light (b) store charge briefly (c) spin a wheel (d) measure heat
2. 2.📏 Which unit measures energy used each second? (a) watt (W) (b) volt (V) (c) ampere (A) (d) ohm (Ω)
3. 3.🌈 In the resistor colour code, which number does yellow stand for?
4. 4.📏 How many amperes (A) is 940 mA? =
5. 5.True or false: a thermistor makes things spin. (a) True (b) False
6. 6.💡 An LED is joined to a 9 V battery through a 1000 Ω resistor; its long leg goes to the − side and its short leg to the + side. What happens? (a) lights up (b) may burn out (c) does not light
7. 7.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 49000 Ω resistor? (a) yellow-white-yellow (b) white-yellow-orange (c) yellow-white-red (d) yellow-white-orange
8. 8.True or false: the voltmeter is joined across a part. (a) False (b) True
9. 9.True or false: on an LED, the shorter leg is the cathode (−). (a) False (b) True
10. 10.🧾 A 200 W appliance runs for 4 hours. How many units (kWh) of electricity does it use? =
11. 11.🧾 A 60 W filament bulb is swapped for a 9 W LED lamp that gives about the same light. Both would run for 1 hour. How many watt-hours (Wh) are saved?
12. 12.💡 On an LED, is the longer leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
13. 13.📏 How many watts (W) is 0.1 kW?
14. 14.🔺 A current of 40 mA flows through a 150 Ω resistor. What is the voltage across it (in volts)? =
15. 15.⚡ A home appliance on the 230 V mains takes 0.5 A. What is its power (in watts)?
16. 16.🔺 A current of 0.1 A flows through an 8 Ω resistor. What is the voltage across it (in volts)? =
17. 17.🔺 A current of 0.1 A flows when 0.8 V is joined across a resistor. What is its resistance (in ohms)?
18. 18.🔺 In the V-I-R triangle, how do we find V? (a) V = I × R (b) V = R ÷ I (c) V = I ÷ R (d) V = I + R
19. 19.🧾 One “unit” on an electricity bill is … (a) 1 volt (b) 1 kilowatt-hour (kWh) (c) 1 watt (d) 1 ampere
20. 20.🌈 A resistor has the colour bands yellow, black, yellow. What is its value in kilo-ohms (kΩ)? =
21. 21.🧾 A 200 W appliance runs for 5 hours. How many units (kWh) of electricity does it use? =
22. 22.🌈 A gold fourth band on a resistor means the value may be off by … (a) 50 % (b) 0 % (c) 5 % (d) 25 %
23. 23.🧮 Four equal 80 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 = V ÷ I (b) R = V × I (c) R = V + I (d) R = I ÷ V
25. 25.⚡ A device works on 5 V and takes 2 A. What is its power (in watts)? =
26. 26.What does a transistor do? (a) boosts a small signal (b) turns a fan or wheels (c) glows using little power (d) blows if current is high
27. 27.📏 Which unit measures current? (a) ohm (Ω) (b) volt (V) (c) watt (W) (d) ampere (A)
28. 28.⚡ A 2.25 W device works on 9 V. What current does it take (in amperes)? =
29. 29.💡 An LED is joined to a 9 V battery with no resistor; the leg next to the flat edge of its rim goes to the − side. What happens? (a) does not light (b) may burn out (c) lights up
30. 30.🔺 A current of 2 A flows through a 20 Ω resistor. What is the voltage across it (in volts)? =
31. 31.🔺 A current of 50 mA flows through a 200 Ω resistor. What is the voltage across it (in volts)? =
32. 32.🔺 A 0.4 V supply is joined across a 4 Ω resistor. What current flows (in amperes)? =
33. 33.🧾 A family uses 30 units of electricity in a month and each unit costs ₹8. What is the bill (in ₹)?
34. 34.📏 In the water-pipe picture of a circuit, resistance is like … (a) a bigger tank (b) a narrow pipe (c) the water pressure (d) the flow of water
35. 35.💡 A blue LED uses 3 V and should get 20 mA. It runs from a 6 V supply. What resistor (in ohms) is needed in series?
36. 36.True or false: the push of a cell is measured in volts (V). (a) True (b) False
37. 37.🌈 A resistor has the colour bands brown, blue, brown. What is its value (in ohms)?
38. 38.🧩 Which part changes electrical energy into sound? (a) a capacitor (b) a diode (c) a buzzer (d) a resistor
39. 39.🧮 Two equal 20 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
40. 40.Which of these wastes electricity? (a) close the fridge quickly (b) use LED lamps (c) unplug idle chargers (d) leave the TV on standby

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