Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 275 · 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 red LED (it uses 2 V) is joined with a 100 Ω resistor to a 3 V supply. What current flows (in mA)?
2. 2.🧩 Which part changes electrical energy into movement? (a) a motor (b) a fuse (c) an LED (d) a resistor
3. 3.⚡ A home appliance on the 230 V mains takes 0.5 A. What is its power (in watts)?
4. 4.🔺 In the V-I-R triangle, how do we find V? (a) V = R ÷ I (b) V = I × R (c) V = I ÷ R (d) V = I + R
5. 5.⚡ A device works on 9 V and takes 1.5 A. What is its power (in watts)? =
6. 6.🧮 Resistors of 47 Ω and 20 Ω are joined in series. What is the total resistance (in ohms)?
7. 7.📏 Which unit measures energy used each second? (a) volt (V) (b) ampere (A) (c) ohm (Ω) (d) watt (W)
8. 8.💡 Does it save or waste electricity to leave fridge door open? (a) saves electricity (b) wastes electricity
9. 9.🔺 A current of 20 mA flows through a 120 Ω resistor. What is the voltage across it (in volts)? =
10. 10.🧾 A 1500 W appliance runs for 4 hours. How many units (kWh) of electricity does it use? =
11. 11.True or false: a thermistor senses how hot it is. (a) True (b) False
12. 12.🔺 A current of 2.5 A flows through a 2 Ω resistor. What is the voltage across it (in volts)? =
13. 13.⚡ A 1.2 W device works on 6 V. What current does it take (in amperes)? =
14. 14.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) gets smaller (b) becomes zero (c) stays the same (d) gets bigger
15. 15.🧮 Adding another resistor in series makes the total resistance … (a) zero (b) smaller (c) bigger (d) stay the same
16. 16.🧾 Which lamp gives the same light for the least power? (a) a filament bulb (b) a candle (c) an oil lamp (d) an LED lamp
17. 17.True or false: on an LED, the leg by the flat edge is the anode (+). (a) False (b) True
18. 18.True or false: a resistor limits the current. (a) True (b) False
19. 19.⚡ A 1.2 W device works on 12 V. What current does it take (in amperes)? =
20. 20.🌈 A resistor has the colour bands white, yellow, brown. What is its value (in ohms)?
21. 21.📏 How many kilowatts (kW) is 4950 W? =
22. 22.🧮 Resistors of 22 Ω and 22 Ω are joined in series. What is the total resistance (in ohms)?
23. 23.💡 On an LED, is the shorter leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
24. 24.🔺 A current of 3 A flows through a 4 Ω resistor. What is the voltage across it (in volts)? =
25. 25.🔺 A 2.5 V supply is joined across a 250 Ω resistor. What current flows (in milliamperes, mA)?
26. 26.🔺 A current of 3 A flows through a 5 Ω resistor. What is the voltage across it (in volts)? =
27. 27.🌈 A resistor has the colour bands grey, blue, red. What is its value (in ohms)?
28. 28.🔺 A current of 2.5 A flows through an 8 Ω resistor. What is the voltage across it (in volts)? =
29. 29.📏 Which unit measures how much a part resists? (a) volt (V) (b) watt (W) (c) ohm (Ω) (d) ampere (A)
30. 30.🧮 Resistors of 22 Ω and 68 Ω are joined in series. What is the total resistance (in ohms)?
31. 31.🧩 Which part changes electrical energy into sound? (a) a resistor (b) a capacitor (c) a buzzer (d) a diode
32. 32.⚡ Which formula gives electric power? (a) P = V × I (b) P = V ÷ I (c) P = I ÷ V (d) P = V + I
33. 33.⚡ A 13.5 W device works on 9 V. What current does it take (in amperes)? =
34. 34.True or false: an LDR lets current go one way. (a) False (b) True
35. 35.True or false: to close the fridge quickly wastes electricity. (a) True (b) False
36. 36.🌈 A resistor has the colour bands green, blue, red. What is its value (in ohms)?
37. 37.🔺 A current of 0.2 A flows through a 5 Ω resistor. What is the voltage across it (in volts)? =
38. 38.⚡ A home appliance on the 230 V mains takes 5 A. What is its power (in watts)?
39. 39.🔺 A current of 25 mA flows through a 330 Ω resistor. What is the voltage across it (in volts)? =
40. 40.📏 Which unit measures current? (a) volt (V) (b) ampere (A) (c) ohm (Ω) (d) watt (W)

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