Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 858 · 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 family uses 190 units of electricity in a month and each unit costs ₹5. What is the bill (in ₹)?
2. 2.⚡ A 0.9 W device works on 9 V. What current does it take (in amperes)? =
3. 3.💡 What happens if an LED is put in backwards? (a) it changes colour (b) it makes a sound (c) it lights brighter (d) it does not light
4. 4.🔺 A current of 0.25 A flows when 1 V is joined across a resistor. What is its resistance (in ohms)?
5. 5.🔺 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
6. 6.⚡ A device works on 12 V and takes 1.5 A. What is its power (in watts)? =
7. 7.🧩 Which component senses how bright it is? (a) thermistor (b) LDR (c) fuse (d) transistor
8. 8.🔺 A current of 0.25 A flows through a 15 Ω resistor. What is the voltage across it (in volts)? =
9. 9.True or false: on an LED, the leg by the flat edge is the anode (+). (a) False (b) True
10. 10.💡 A red LED uses 2 V and should get 10 mA. It runs from a 9 V supply. What resistor (in ohms) is needed in series?
11. 11.What does a thermistor do? (a) stores a little charge (b) smooths a wobbly supply (c) senses how hot it is (d) blows if current is high
12. 12.Which of these saves electricity? (a) leave fridge door open (b) leave the TV on standby (c) iron one shirt at a time (d) use daylight to read
13. 13.💡 Does it save or waste electricity to set the AC to 24 °C? (a) saves electricity (b) wastes electricity
14. 14.⚡ Which formula gives electric power? (a) P = I ÷ V (b) P = V × I (c) P = V ÷ I (d) P = V + I
15. 15.⚡ A device works on 3 V and takes 0.1 A. What is its power (in watts)? =
16. 16.💡 On an LED, is the round-side leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
17. 17.🔺 A current of 2 A flows when 16 V is joined across a resistor. What is its resistance (in ohms)?
18. 18.Which of these is measured in ohms (Ω)? (a) how much a part resists (b) the flow of charge (c) current (d) the push of a cell
19. 19.🔍 Which is the odd one out? (a) run fans in empty rooms (b) iron one shirt at a time (c) use old filament bulbs (d) unplug idle chargers
20. 20.⚡ A 12 W device works on 24 V. What current does it take (in amperes)? =
21. 21.True or false: a motor turns a fan or wheels. (a) False (b) True
22. 22.🧮 A 1.6 V battery is joined to 12 Ω and 4 Ω resistors in series. What current flows (in amperes)? =
23. 23.🧮 Five equal 125 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
24. 24.⚡ A home appliance on the 230 V mains takes 5 A. What is its power (in watts)?
25. 25.💡 Does it save or waste electricity to leave the TV on standby? (a) wastes electricity (b) saves electricity
26. 26.🔺 A current of 0.2 A flows through an 8 Ω resistor. What is the voltage across it (in volts)? =
27. 27.🔺 A current of 20 mA flows through a 220 Ω resistor. What is the voltage across it (in volts)? =
28. 28.⚡ A device works on 24 V and takes 0.2 A. What is its power (in watts)? =
29. 29.🧾 A 75 W filament bulb is swapped for a 12 W LED lamp that gives about the same light. Both would run for 3 hours. How many watt-hours (Wh) are saved?
30. 30.🔺 In the V-I-R triangle, how do we find I? (a) I = V + R (b) I = V ÷ R (c) I = R ÷ V (d) I = V × R
31. 31.🔺 A 5 V supply is joined across a 250 Ω resistor. What current flows (in milliamperes, mA)?
32. 32.🔺 A current of 50 mA flows when 20 V is joined across a resistor. What is its resistance (in ohms)?
33. 33.🌈 A resistor has the colour bands violet, violet, orange. What is its value (in ohms)?
34. 34.🌈 A resistor has the colour bands blue, white, orange. What is its value (in ohms)?
35. 35.True or false: a fuse smooths a wobbly supply. (a) True (b) False
36. 36.🔺 A current of 0.1 A flows when 1.5 V is joined across a resistor. What is its resistance (in ohms)?
37. 37.🧮 Resistors of 22 Ω, 220 Ω and 22 Ω are joined in series. What is the total resistance (in ohms)?
38. 38.🧮 Two equal 100 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
39. 39.🔺 In the V-I-R triangle, how do we find R? (a) R = I ÷ V (b) R = V + I (c) R = V × I (d) R = V ÷ I
40. 40.⚡ A device works on 6 V and takes 0.25 A. What is its power (in watts)? =

Free electronics lessons, practice and worksheets at talentjr.in/electronics-for-kids