Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 338 · 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 0.5 V supply is joined across a 2 Ω resistor. What current flows (in amperes)? =
2. 2.🧩 Which part changes electrical energy into movement? (a) a motor (b) an LED (c) a resistor (d) a fuse
3. 3.🔺 A current of 10 mA flows through a 120 Ω resistor. What is the voltage across it (in volts)? =
4. 4.🔺 A current of 2 A flows through a 3 Ω resistor. What is the voltage across it (in volts)? =
5. 5.🌈 A resistor has the colour bands orange, black, red. What is its value in kilo-ohms (kΩ)? =
6. 6.🔍 Which is the odd one out? (a) leave fridge door open (b) use LED lamps (c) use daylight to read (d) switch off empty rooms
7. 7.🌈 A resistor has the colour bands white, brown, red. What is its value (in ohms)?
8. 8.🔺 A current of 25 mA flows through a 100 Ω resistor. What is the voltage across it (in volts)? =
9. 9.🌈 A gold fourth band on a resistor means the value may be off by … (a) 50 % (b) 25 % (c) 0 % (d) 5 %
10. 10.🔺 A current of 0.25 A flows through a 6 Ω resistor. What is the voltage across it (in volts)? =
11. 11.🔺 A current of 0.25 A flows when 1.25 V is joined across a resistor. What is its resistance (in ohms)?
12. 12.📏 In the water-pipe picture of a circuit, voltage is like … (a) the water pressure (b) the tap handle (c) the pipe colour (d) the water tank lid
13. 13.💡 On an LED, is the round-side leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
14. 14.🧮 Resistors of 33 Ω and 22 Ω are joined in series. What is the total resistance (in ohms)?
15. 15.📏 Voltmeter or ammeter: which one measures voltage? (a) ammeter (b) voltmeter
16. 16.🧾 A 100 W filament bulb is swapped for a 15 W LED lamp that gives about the same light. Both would run for 1 hour. How many watt-hours (Wh) are saved?
17. 17.🌈 A resistor has the colour bands orange, yellow, red. What is its value in kilo-ohms (kΩ)? =
18. 18.💡 On an LED, is the longer leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
19. 19.🌈 A resistor has the colour bands brown, red, black. What is its value (in ohms)?
20. 20.True or false: to unplug idle chargers saves electricity. (a) False (b) True
21. 21.Which of these saves electricity? (a) iron one shirt at a time (b) use old filament bulbs (c) leave the TV on standby (d) switch off empty rooms
22. 22.🔍 Which is the odd one out? (a) leave the TV on standby (b) unplug idle chargers (c) switch off empty rooms (d) use LED lamps
23. 23.💡 Does it save or waste electricity to use old filament bulbs? (a) saves electricity (b) wastes electricity
24. 24.⚡ A device works on 9 V and takes 0.2 A. What is its power (in watts)? =
25. 25.🧾 A family uses 150 units of electricity in a month and each unit costs ₹4. What is the bill (in ₹)?
26. 26.True or false: on an LED, the longer leg is the cathode (−). (a) False (b) True
27. 27.True or false: on an LED, the leg by the flat edge is the anode (+). (a) False (b) True
28. 28.🌈 A resistor has the colour bands violet, yellow, orange. What is its value in kilo-ohms (kΩ)? =
29. 29.🌈 A resistor has the colour bands yellow, yellow, orange. What is its value (in ohms)?
30. 30.True or false: a motor turns a fan or wheels. (a) False (b) True
31. 31.🔺 A current of 10 mA flows through a 500 Ω resistor. What is the voltage across it (in volts)? =
32. 32.📏 How many milliamperes (mA) is 1.27 A?
33. 33.📏 Which unit measures current? (a) ampere (A) (b) ohm (Ω) (c) watt (W) (d) volt (V)
34. 34.⚡ Which formula gives electric power? (a) P = V × I (b) P = V ÷ I (c) P = V + I (d) P = I ÷ V
35. 35.🔺 A current of 25 mA flows through a 120 Ω resistor. What is the voltage across it (in volts)? =
36. 36.Which of these saves electricity? (a) run fans in empty rooms (b) close the fridge quickly (c) leave fridge door open (d) iron one shirt at a time
37. 37.📏 How many amperes (A) is 2820 mA? =
38. 38.🔺 An 11 V supply is joined across a 220 Ω resistor. What current flows (in milliamperes, mA)?
39. 39.True or false: on an LED, the shorter leg is the cathode (−). (a) False (b) True
40. 40.🔺 A current of 1.5 A flows through a 15 Ω resistor. What is the voltage across it (in volts)? =

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