Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 932 · 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 100 Ω resistor is joined in series with two equal 330 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
2. 2.📏 Which unit measures resistance? (a) ohm (Ω) (b) volt (V) (c) ampere (A) (d) watt (W)
3. 3.🧾 A family uses 30 units of electricity in a month and each unit costs ₹5. What is the bill (in ₹)?
4. 4.True or false: the ammeter measures voltage. (a) True (b) False
5. 5.True or false: a motor limits the current. (a) True (b) False
6. 6.💡 An LED is joined to a 5 V battery with no resistor; its long leg goes to the + side and its short leg to the − side. What happens? (a) may burn out (b) does not light (c) lights up
7. 7.🔺 A current of 3 A flows through a 6 Ω resistor. What is the voltage across it (in volts)? =
8. 8.🌈 A resistor has the colour bands red, black, red. What is its value (in ohms)?
9. 9.💡 A red LED (it uses 2 V) is joined with a 150 Ω resistor to a 3.5 V supply. What current flows (in mA)?
10. 10.🧮 Resistors of 50 Ω, 20 Ω and 330 Ω are joined in series. What is the total resistance (in ohms)?
11. 11.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 3600 Ω resistor? (a) orange-blue-red (b) orange-blue-orange (c) blue-orange-red (d) orange-blue-brown
12. 12.🔺 A current of 25 mA flows through a 500 Ω resistor. What is the voltage across it (in volts)? =
13. 13.True or false: on an LED, the leg by the flat edge is the cathode (−). (a) False (b) True
14. 14.⚡ Which formula gives electric power? (a) P = V + I (b) P = V × I (c) P = V ÷ I (d) P = I ÷ V
15. 15.🧾 A 100 W appliance runs for 10 hours. How many units (kWh) of electricity does it use? =
16. 16.⚡ A device works on 5 V and takes 0.2 A. What is its power (in watts)? =
17. 17.📏 How many ohms make 1 kilo-ohm (kΩ)? (a) 10 (b) 1024 (c) 100 (d) 1000
18. 18.🔺 A current of 40 mA flows through a 400 Ω resistor. What is the voltage across it (in volts)? =
19. 19.💡 A red LED (it uses 2 V) is joined with a 100 Ω resistor to a 3 V supply. What current flows (in mA)?
20. 20.🔺 A current of 0.25 A flows through a 4 Ω resistor. What is the voltage across it (in volts)? =
21. 21.🔺 A current of 1 A flows through a 12 Ω resistor. What is the voltage across it (in volts)? =
22. 22.🧩 Which component makes things spin? (a) fuse (b) diode (c) motor (d) thermistor
23. 23.True or false: a transistor boosts a small signal. (a) False (b) True
24. 24.💡 What happens if an LED is put in backwards? (a) it does not light (b) it changes colour (c) it makes a sound (d) it lights brighter
25. 25.🔺 A current of 10 mA flows when 3.3 V is joined across a resistor. What is its resistance (in ohms)?
26. 26.🔺 A 0.2 V supply is joined across a 2 Ω resistor. What current flows (in amperes)? =
27. 27.True or false: current is measured in amperes (A). (a) False (b) True
28. 28.🌈 A gold fourth band on a resistor means the value may be off by … (a) 50 % (b) 25 % (c) 5 % (d) 0 %
29. 29.🌈 A resistor has the colour bands violet, grey, orange. What is its value in kilo-ohms (kΩ)? =
30. 30.🌈 A resistor has the colour bands green, red, brown. What is its value (in ohms)?
31. 31.🌈 In the resistor colour code, which number does blue stand for?
32. 32.🔺 A current of 50 mA flows through a 150 Ω resistor. What is the voltage across it (in volts)? =
33. 33.🔺 A current of 0.2 A flows when 2 V is joined across a resistor. What is its resistance (in ohms)?
34. 34.🧮 Adding another resistor in series makes the total resistance … (a) stay the same (b) bigger (c) zero (d) smaller
35. 35.🧾 A 100 W appliance runs for 4 hours. How many units (kWh) of electricity does it use? =
36. 36.🌈 Which band is read first on a resistor? (a) the widest gap (b) the gold band (c) any band (d) the one nearest an end
37. 37.📏 Voltmeter or ammeter: which one is joined in series? (a) voltmeter (b) ammeter
38. 38.💡 A red LED uses 2 V and should get 10 mA. It runs from a 6 V supply. What resistor (in ohms) is needed in series?
39. 39.True or false: an LDR stores a little charge. (a) True (b) False
40. 40.🧩 Which part changes electrical energy into sound? (a) a capacitor (b) a resistor (c) a buzzer (d) a diode

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