Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 209 · 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.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) becomes zero (b) gets bigger (c) stays the same (d) gets smaller
2. 2.📏 Which unit measures energy used each second? (a) volt (V) (b) watt (W) (c) ohm (Ω) (d) ampere (A)
3. 3.🔺 In the V-I-R triangle, how do we find R? (a) R = V + I (b) R = V × I (c) R = I ÷ V (d) R = V ÷ I
4. 4.🔺 A 0.2 V supply is joined across a 2 Ω resistor. What current flows (in amperes)? =
5. 5.🔺 An 18.8 V supply is joined across a 470 Ω resistor. What current flows (in milliamperes, mA)?
6. 6.📏 How many milliamperes (mA) make 1 ampere? (a) 1000 (b) 60 (c) 10 (d) 100
7. 7.📏 How many ohms make 1 kilo-ohm (kΩ)? (a) 10 (b) 1000 (c) 1024 (d) 100
8. 8.💡 On an LED, is the leg by the flat edge the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
9. 9.🧮 Two equal 40 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
10. 10.True or false: a capacitor glows using little power. (a) True (b) False
11. 11.📏 How many watts (W) is 4 kW?
12. 12.💡 A red LED (it uses 2 V) is joined with a 300 Ω resistor to a 6.5 V supply. What current flows (in mA)?
13. 13.📏 Voltmeter or ammeter: which one measures current? (a) voltmeter (b) ammeter
14. 14.📏 How many milliamperes (mA) is 0.99 A?
15. 15.💡 On an LED, is the round-side leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
16. 16.🧾 One “unit” on an electricity bill is … (a) 1 watt (b) 1 ampere (c) 1 volt (d) 1 kilowatt-hour (kWh)
17. 17.🔺 A current of 10 mA flows through a 200 Ω resistor. What is the voltage across it (in volts)? =
18. 18.📏 Voltmeter or ammeter: which one is joined in series? (a) voltmeter (b) ammeter
19. 19.🔍 Which is the odd one out? (a) close the fridge quickly (b) switch off empty rooms (c) leave fridge door open (d) use LED lamps
20. 20.🧾 A 60 W filament bulb is swapped for a 9 W LED lamp that gives about the same light. Both would run for 8 hours. How many watt-hours (Wh) are saved?
21. 21.🔺 A current of 3 A flows when 45 V is joined across a resistor. What is its resistance (in ohms)?
22. 22.True or false: a buzzer beeps for an alarm. (a) True (b) False
23. 23.🧮 A 470 Ω resistor is joined in series with two equal 100 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
24. 24.📏 How many milliamperes (mA) is 0.54 A?
25. 25.🔺 A current of 10 mA flows through a 400 Ω resistor. What is the voltage across it (in volts)? =
26. 26.🌈 A gold fourth band on a resistor means the value may be off by … (a) 25 % (b) 0 % (c) 5 % (d) 50 %
27. 27.⚡ Which formula gives electric power? (a) P = I ÷ V (b) P = V × I (c) P = V + I (d) P = V ÷ I
28. 28.🔺 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
29. 29.What does a motor do? (a) blows if current is high (b) limits the current (c) makes things spin (d) senses how bright it is
30. 30.🔺 A current of 2.5 A flows when 37.5 V is joined across a resistor. What is its resistance (in ohms)?
31. 31.🌈 In the resistor colour code, which number does green stand for?
32. 32.⚡ A home appliance on the 230 V mains takes 2 A. What is its power (in watts)?
33. 33.🔺 A 16 V supply is joined across an 8 Ω resistor. What current flows (in amperes)? =
34. 34.🧾 A 60 W filament bulb is swapped for a 9 W LED lamp that gives about the same light. Both would run for 10 hours. How many watt-hours (Wh) are saved?
35. 35.🧮 A 1 V battery is joined to 2 Ω and 8 Ω resistors in series. What current flows (in amperes)? =
36. 36.💡 On an LED, is the longer leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
37. 37.🧮 Two equal 100 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
38. 38.🧩 Which component stores a little charge? (a) fuse (b) LED (c) resistor (d) capacitor
39. 39.🔺 A current of 50 mA flows when 23.5 V is joined across a resistor. What is its resistance (in ohms)?
40. 40.🧮 A 470 Ω resistor is joined in series with two equal 10 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?

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