Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 561 · 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 current of 2 A flows through a 5 Ω resistor. What is the voltage across it (in volts)? =
2. 2.💡 On an LED, is the longer leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
3. 3.⚡ A home appliance on the 230 V mains takes 2 A. What is its power (in watts)?
4. 4.🔺 A current of 0.25 A flows when 1.25 V is joined across a resistor. What is its resistance (in ohms)?
5. 5.🌈 A resistor has the colour bands violet, red, yellow. What is its value in kilo-ohms (kΩ)? =
6. 6.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 3700 Ω resistor? (a) orange-violet-red (b) orange-violet-orange (c) violet-orange-red (d) orange-violet-brown
7. 7.🌈 A resistor has the colour bands grey, green, red. What is its value in kilo-ohms (kΩ)? =
8. 8.Which of these is measured in ohms (Ω)? (a) how much a part resists (b) the push of a cell (c) the flow of charge (d) current
9. 9.🧾 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?
10. 10.📏 Which unit measures power? (a) watt (W) (b) ohm (Ω) (c) volt (V) (d) ampere (A)
11. 11.True or false: to leave fridge door open wastes electricity. (a) False (b) True
12. 12.What does a resistor do? (a) makes a beeping sound (b) has coloured bands (c) makes things spin (d) smooths a wobbly supply
13. 13.🔺 A current of 0.25 A flows through a 15 Ω resistor. What is the voltage across it (in volts)? =
14. 14.🌈 Which band is read first on a resistor? (a) the gold band (b) the widest gap (c) the one nearest an end (d) any band
15. 15.🔺 A 0.6 V supply is joined across a 3 Ω resistor. What current flows (in amperes)? =
16. 16.🧮 A 220 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)?
17. 17.True or false: to leave fridge door open saves electricity. (a) False (b) True
18. 18.🔺 A 60 V supply is joined across a 20 Ω resistor. What current flows (in amperes)? =
19. 19.🌈 In the resistor colour code, which number does green stand for?
20. 20.📏 Voltmeter or ammeter: which one measures voltage? (a) ammeter (b) voltmeter
21. 21.True or false: a thermistor senses how hot it is. (a) True (b) False
22. 22.💡 An LED is joined to a 6 V battery with no resistor; its long leg goes to the + side and its short leg to the − side. What happens? (a) does not light (b) lights up (c) may burn out
23. 23.⚡ A device works on 12 V and takes 0.5 A. What is its power (in watts)? =
24. 24.True or false: on an LED, the round-side leg is the anode (+). (a) True (b) False
25. 25.🧩 Which component smooths a wobbly supply? (a) capacitor (b) thermistor (c) transistor (d) fuse
26. 26.🔺 A current of 0.2 A flows through a 10 Ω resistor. What is the voltage across it (in volts)? =
27. 27.🧮 A 33 Ω resistor is joined in series with two equal 20 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
28. 28.🔺 A 1.25 V supply is joined across a 5 Ω resistor. What current flows (in amperes)? =
29. 29.⚡ A home appliance on the 230 V mains takes 10 A. What is its power (in watts)?
30. 30.⚡ A home appliance on the 230 V mains takes 4 A. What is its power (in watts)?
31. 31.🧩 Which component makes things spin? (a) transistor (b) buzzer (c) LED (d) motor
32. 32.🔺 A current of 10 mA flows through a 330 Ω resistor. What is the voltage across it (in volts)? =
33. 33.🔺 In the V-I-R triangle, how do we find V? (a) V = I ÷ R (b) V = I + R (c) V = I × R (d) V = R ÷ I
34. 34.⚡ A home appliance on the 230 V mains takes 1.5 A. What is its power (in watts)?
35. 35.True or false: resistance is measured in watts (W). (a) False (b) True
36. 36.💡 What happens if an LED is put in backwards? (a) it makes a sound (b) it does not light (c) it lights brighter (d) it changes colour
37. 37.🔺 A current of 20 mA flows through a 330 Ω resistor. What is the voltage across it (in volts)? =
38. 38.⚡ A 10 W device works on 5 V. What current does it take (in amperes)? =
39. 39.🧮 Two equal 10 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
40. 40.True or false: on an LED, the leg by the flat edge is the anode (+). (a) True (b) False

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