Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 215 · 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.📏 How many kilo-ohms (kΩ) is 3100 Ω? =
2. 2.True or false: to unplug idle chargers wastes electricity. (a) True (b) False
3. 3.True or false: current is measured in volts (V). (a) True (b) False
4. 4.⚡ A device works on 3 V and takes 1.5 A. What is its power (in watts)? =
5. 5.📏 Which unit measures resistance? (a) ohm (Ω) (b) volt (V) (c) watt (W) (d) ampere (A)
6. 6.🔺 A 2 V supply is joined across a 200 Ω resistor. What current flows (in milliamperes, mA)?
7. 7.⚡ Which formula gives electric power? (a) P = I ÷ V (b) P = V × I (c) P = V + I (d) P = V ÷ I
8. 8.🔺 A current of 0.5 A flows when 6 V is joined across a resistor. What is its resistance (in ohms)?
9. 9.💡 On an LED, is the leg by the flat edge the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
10. 10.Which of these saves electricity? (a) leave fridge door open (b) use LED lamps (c) iron one shirt at a time (d) use old filament bulbs
11. 11.⚡ A 0.15 W device works on 1.5 V. What current does it take (in amperes)? =
12. 12.Which of these is measured in amperes (A)? (a) power (b) voltage (c) current (d) resistance
13. 13.🔺 A current of 0.1 A flows through a 5 Ω resistor. What is the voltage across it (in volts)? =
14. 14.🧮 Adding another resistor in series makes the total resistance … (a) stay the same (b) bigger (c) smaller (d) zero
15. 15.⚡ A home appliance on the 230 V mains takes 10 A. What is its power (in watts)?
16. 16.🧾 A 60 W filament bulb is swapped for a 9 W LED lamp that gives about the same light. Both would run for 3 hours. How many watt-hours (Wh) are saved?
17. 17.⚡ A 48 W device works on 24 V. What current does it take (in amperes)? =
18. 18.🌈 A resistor has the colour bands brown, red, yellow. What is its value in kilo-ohms (kΩ)? =
19. 19.⚡ A 10 W device works on 5 V. What current does it take (in amperes)? =
20. 20.🧩 Which part changes electrical energy into sound? (a) a resistor (b) a diode (c) a buzzer (d) a capacitor
21. 21.🔺 A current of 2 A flows through a 10 Ω resistor. What is the voltage across it (in volts)? =
22. 22.💡 On an LED, is the longer leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
23. 23.🧮 Resistors of 20 Ω and 150 Ω are joined in series. What is the total resistance (in ohms)?
24. 24.⚡ A home appliance on the 230 V mains takes 0.5 A. What is its power (in watts)?
25. 25.🔺 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
26. 26.📏 Which unit measures power? (a) ohm (Ω) (b) volt (V) (c) ampere (A) (d) watt (W)
27. 27.📏 How many ohms make 1 kilo-ohm (kΩ)? (a) 1000 (b) 10 (c) 100 (d) 1024
28. 28.🔺 A current of 2 A flows when 20 V is joined across a resistor. What is its resistance (in ohms)?
29. 29.🔺 A current of 2.5 A flows through a 6 Ω resistor. What is the voltage across it (in volts)? =
30. 30.🌈 A resistor has the colour bands brown, orange, yellow. What is its value in kilo-ohms (kΩ)? =
31. 31.💡 On an LED, is the round-side leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
32. 32.🧾 A 40 W filament bulb is swapped for a 6 W LED lamp that gives about the same light. Both would run for 4 hours. How many watt-hours (Wh) are saved?
33. 33.🧮 Three equal 30 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
34. 34.🧮 Two equal 1000 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
35. 35.True or false: energy used each second is measured in watts (W). (a) False (b) True
36. 36.🌈 A gold fourth band on a resistor means the value may be off by … (a) 50 % (b) 25 % (c) 5 % (d) 0 %
37. 37.🔺 A current of 20 mA flows when 6.6 V is joined across a resistor. What is its resistance (in ohms)?
38. 38.💡 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) does not light (c) may burn out
39. 39.🔺 A current of 2.5 A flows through an 8 Ω resistor. What is the voltage across it (in volts)? =
40. 40.True or false: to run fans in empty rooms saves electricity. (a) True (b) False

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