Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 397 · 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.True or false: the voltmeter measures current. (a) False (b) True
2. 2.🧩 Which part changes electrical energy into sound? (a) a resistor (b) a capacitor (c) a buzzer (d) a diode
3. 3.🧮 Resistors of 33 Ω and 330 Ω are joined in series. What is the total resistance (in ohms)?
4. 4.🔺 A 12.5 V supply is joined across a 500 Ω resistor. What current flows (in milliamperes, mA)?
5. 5.🔺 A current of 1.5 A flows through a 10 Ω resistor. What is the voltage across it (in volts)? =
6. 6.🔺 A 30 V supply is joined across a 20 Ω resistor. What current flows (in amperes)? =
7. 7.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) gets bigger (b) becomes zero (c) gets smaller (d) stays the same
8. 8.🌈 In the resistor colour code, which number does green stand for?
9. 9.📏 Which unit measures current? (a) watt (W) (b) volt (V) (c) ampere (A) (d) ohm (Ω)
10. 10.📏 In the water-pipe picture of a circuit, resistance is like … (a) a bigger tank (b) the water pressure (c) a narrow pipe (d) the flow of water
11. 11.📏 Voltmeter or ammeter: which one measures current? (a) voltmeter (b) ammeter
12. 12.🧩 Which component stores a little charge? (a) fuse (b) LED (c) motor (d) capacitor
13. 13.⚡ A device works on 3 V and takes 1.5 A. What is its power (in watts)? =
14. 14.💡 A red LED (it uses 2 V) is joined with a 100 Ω resistor to a 3 V supply. What current flows (in mA)?
15. 15.📏 How many ohms make 1 kilo-ohm (kΩ)? (a) 10 (b) 1024 (c) 100 (d) 1000
16. 16.🔺 In the V-I-R triangle, how do we find R? (a) R = V × I (b) R = I ÷ V (c) R = V + I (d) R = V ÷ I
17. 17.💡 On an LED, is the shorter leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
18. 18.🧮 Two equal 40 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
19. 19.🧩 Which component senses how hot it is? (a) transistor (b) potentiometer (c) motor (d) thermistor
20. 20.💡 On an LED, is the longer leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
21. 21.💡 Why does an LED need a resistor in series? (a) to make it brighter (b) to change its colour (c) to store charge (d) to limit the current
22. 22.⚡ A home appliance on the 230 V mains takes 8 A. What is its power (in watts)?
23. 23.⚡ Power tells us … (a) the colour of light (b) energy used each second (c) the length of a wire (d) the size of a cell
24. 24.Which of these is measured in amperes (A)? (a) how much a part resists (b) the flow of charge (c) power (d) resistance
25. 25.🌈 A gold fourth band on a resistor means the value may be off by … (a) 5 % (b) 50 % (c) 0 % (d) 25 %
26. 26.📏 Which unit measures energy used each second? (a) ampere (A) (b) volt (V) (c) watt (W) (d) ohm (Ω)
27. 27.🔺 In the V-I-R triangle, how do we find I? (a) I = R ÷ V (b) I = V ÷ R (c) I = V + R (d) I = V × R
28. 28.📏 Which unit measures resistance? (a) ampere (A) (b) watt (W) (c) ohm (Ω) (d) volt (V)
29. 29.Which of these wastes electricity? (a) use old filament bulbs (b) set the AC to 24 °C (c) switch off empty rooms (d) use daylight to read
30. 30.📏 How many watts (W) is 4.3 kW?
31. 31.🌈 In the resistor colour code, which number does violet stand for?
32. 32.🧾 Which lamp gives the same light for the least power? (a) an LED lamp (b) a candle (c) an oil lamp (d) a filament bulb
33. 33.What does a transistor do? (a) boosts a small signal (b) senses how hot it is (c) smooths a wobbly supply (d) makes things spin
34. 34.⚡ A home appliance on the 230 V mains takes 0.5 A. What is its power (in watts)?
35. 35.🧮 Adding another resistor in series makes the total resistance … (a) stay the same (b) smaller (c) bigger (d) zero
36. 36.🔺 A current of 40 mA flows through a 120 Ω resistor. What is the voltage across it (in volts)? =
37. 37.🌈 A resistor has the colour bands white, green, red. What is its value (in ohms)?
38. 38.🌈 A resistor has the colour bands yellow, yellow, orange. What is its value in kilo-ohms (kΩ)? =
39. 39.🌈 A resistor has the colour bands orange, white, orange. What is its value in kilo-ohms (kΩ)? =
40. 40.Which of these saves electricity? (a) leave fridge door open (b) leave the TV on standby (c) use LED lamps (d) run fans in empty rooms

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