Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 4 · 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.Which of these wastes electricity? (a) close the fridge quickly (b) switch off empty rooms (c) leave the TV on standby (d) unplug idle chargers
2. 2.📏 How many milliamperes (mA) make 1 ampere? (a) 100 (b) 10 (c) 1000 (d) 60
3. 3.🌈 A resistor has the colour bands white, green, brown. What is its value (in ohms)?
4. 4.💡 An LED is joined to a 6 V battery through a 220 Ω resistor; its long leg goes to the + side and its short leg to the − side. What happens? (a) does not light (b) may burn out (c) lights up
5. 5.🔺 In the V-I-R triangle, how do we find I? (a) I = V + R (b) I = V ÷ R (c) I = V × R (d) I = R ÷ V
6. 6.True or false: to use old filament bulbs saves electricity. (a) True (b) False
7. 7.💡 On an LED, is the leg by the flat edge the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
8. 8.🔺 A 1.2 V supply is joined across a 12 Ω resistor. What current flows (in amperes)? =
9. 9.🔺 A current of 2 A flows when 8 V is joined across a resistor. What is its resistance (in ohms)?
10. 10.True or false: on an LED, the leg by the flat edge is the anode (+). (a) True (b) False
11. 11.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) gets bigger (b) becomes zero (c) stays the same (d) gets smaller
12. 12.🧾 Which lamp gives the same light for the least power? (a) a candle (b) a filament bulb (c) an oil lamp (d) an LED lamp
13. 13.🧩 Which component beeps for an alarm? (a) potentiometer (b) LED (c) diode (d) buzzer
14. 14.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 170 Ω resistor? (a) brown-violet-brown (b) violet-brown-brown (c) brown-violet-red (d) brown-violet-black
15. 15.🧾 A 100 W appliance runs for 4 hours. How many units (kWh) of electricity does it use? =
16. 16.💡 Does it save or waste electricity to leave the TV on standby? (a) wastes electricity (b) saves electricity
17. 17.🧾 A family uses 80 units of electricity in a month and each unit costs ₹7. What is the bill (in ₹)?
18. 18.🌈 A resistor has the colour bands orange, brown, brown. What is its value (in ohms)?
19. 19.Which of these saves electricity? (a) leave fridge door open (b) run fans in empty rooms (c) iron one shirt at a time (d) switch off empty rooms
20. 20.⚡ Power tells us … (a) the length of a wire (b) the colour of light (c) energy used each second (d) the size of a cell
21. 21.🧾 A 50 W appliance runs for 10 hours. How many units (kWh) of electricity does it use? =
22. 22.💡 A red LED (it uses 2 V) is joined with a 200 Ω resistor to a 3 V supply. What current flows (in mA)?
23. 23.Which of these is measured in amperes (A)? (a) the flow of charge (b) the push of a cell (c) power (d) voltage
24. 24.🧩 A capacitor in a circuit can … (a) spin a wheel (b) make light (c) measure heat (d) store charge briefly
25. 25.📏 How many watts (W) is 1.7 kW?
26. 26.🔺 A current of 2.5 A flows through an 8 Ω resistor. What is the voltage across it (in volts)? =
27. 27.⚡ Which formula gives electric power? (a) P = V + I (b) P = V × I (c) P = I ÷ V (d) P = V ÷ I
28. 28.🧮 Two equal 10 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
29. 29.⚡ A 4.5 W device works on 1.5 V. What current does it take (in amperes)? =
30. 30.📏 Voltmeter or ammeter: which one measures current? (a) voltmeter (b) ammeter
31. 31.🔺 A current of 2 A flows through a 12 Ω resistor. What is the voltage across it (in volts)? =
32. 32.📏 How many watts (W) is 0.2 kW?
33. 33.💡 Does it save or waste electricity to set the AC to 24 °C? (a) saves electricity (b) wastes electricity
34. 34.🧮 Two equal 470 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
35. 35.🧾 A family uses 130 units of electricity in a month and each unit costs ₹8. What is the bill (in ₹)?
36. 36.🧮 Two equal 40 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
37. 37.True or false: the push of a cell is measured in volts (V). (a) False (b) True
38. 38.🔺 A current of 20 mA flows through a 100 Ω resistor. What is the voltage across it (in volts)? =
39. 39.🌈 A resistor has the colour bands grey, yellow, brown. What is its value (in ohms)?
40. 40.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 52000 Ω resistor? (a) green-red-red (b) red-green-orange (c) green-red-orange (d) green-red-yellow

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