Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 379 · 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 6 V supply is joined across a 120 Ω resistor. What current flows (in milliamperes, mA)?
2. 2.🌈 A resistor has the colour bands white, white, red. What is its value in kilo-ohms (kΩ)? =
3. 3.📏 In the water-pipe picture of a circuit, current is like … (a) the flow of water (b) the water pressure (c) the pipe colour (d) a narrow pipe
4. 4.💡 On an LED, is the leg by the flat edge the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
5. 5.🔺 A current of 0.2 A flows when 0.4 V is joined across a resistor. What is its resistance (in ohms)?
6. 6.🔺 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
7. 7.💡 Does it save or waste electricity to use LED lamps? (a) wastes electricity (b) saves electricity
8. 8.💡 A red LED (it uses 2 V) is joined with a 100 Ω resistor to a 4 V supply. What current flows (in mA)?
9. 9.🌈 A resistor has the colour bands orange, white, red. What is its value in kilo-ohms (kΩ)? =
10. 10.🌈 In the resistor colour code, which number does green stand for?
11. 11.🔺 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
12. 12.🔺 A current of 3 A flows through a 15 Ω resistor. What is the voltage across it (in volts)? =
13. 13.🔺 A current of 0.2 A flows through a 15 Ω resistor. What is the voltage across it (in volts)? =
14. 14.🔺 A 2.2 V supply is joined across a 220 Ω resistor. What current flows (in milliamperes, mA)?
15. 15.🔺 A 0.3 V supply is joined across a 3 Ω resistor. What current flows (in amperes)? =
16. 16.True or false: to switch off empty rooms saves electricity. (a) True (b) False
17. 17.🧩 Which part changes electrical energy into movement? (a) an LED (b) a motor (c) a fuse (d) a resistor
18. 18.📏 Which unit measures the push of a cell? (a) volt (V) (b) ohm (Ω) (c) ampere (A) (d) watt (W)
19. 19.🧩 Which component makes things spin? (a) LED (b) transistor (c) LDR (d) motor
20. 20.🧩 Which component senses how bright it is? (a) LDR (b) diode (c) buzzer (d) capacitor
21. 21.🔺 A current of 50 mA flows through a 150 Ω resistor. What is the voltage across it (in volts)? =
22. 22.🧮 Two equal 20 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
23. 23.🌈 Which band is read first on a resistor? (a) the gold band (b) the one nearest an end (c) the widest gap (d) any band
24. 24.🧮 Three equal 30 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
25. 25.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark an 800 Ω resistor? (a) grey-black-black (b) grey-black-red (c) grey-black-brown (d) white-grey-brown
26. 26.📏 Which unit measures resistance? (a) ampere (A) (b) volt (V) (c) ohm (Ω) (d) watt (W)
27. 27.⚡ A device works on 24 V and takes 2 A. What is its power (in watts)? =
28. 28.True or false: on an LED, the round-side leg is the cathode (−). (a) True (b) False
29. 29.📏 How many milliamperes (mA) make 1 ampere? (a) 1000 (b) 60 (c) 100 (d) 10
30. 30.🔺 A current of 0.25 A flows when 0.75 V is joined across a resistor. What is its resistance (in ohms)?
31. 31.🔺 A current of 20 mA flows when 10 V is joined across a resistor. What is its resistance (in ohms)?
32. 32.🔍 Which is the odd one out? (a) set the AC to 24 °C (b) leave the TV on standby (c) unplug idle chargers (d) use daylight to read
33. 33.What does a capacitor do? (a) makes a beeping sound (b) lets current go one way (c) stores a little charge (d) makes things spin
34. 34.⚡ A home appliance on the 230 V mains takes 5 A. What is its power (in watts)?
35. 35.🔺 A current of 50 mA flows through a 220 Ω resistor. What is the voltage across it (in volts)? =
36. 36.True or false: a transistor boosts a small signal. (a) True (b) False
37. 37.True or false: the ammeter measures voltage. (a) True (b) False
38. 38.🌈 A resistor has the colour bands grey, red, orange. What is its value (in ohms)?
39. 39.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark an 810 Ω resistor? (a) grey-brown-red (b) grey-brown-brown (c) brown-grey-brown (d) grey-brown-black
40. 40.📏 In the water-pipe picture of a circuit, resistance is like … (a) a narrow pipe (b) the flow of water (c) a bigger tank (d) the water pressure

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