Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 551 · 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 4 V supply is joined across a 100 Ω resistor. What current flows (in milliamperes, mA)?
2. 2.What does an LED do? (a) makes a beeping sound (b) is a resistance knob (c) lets current go one way (d) glows using little power
3. 3.⚡ Which formula gives electric power? (a) P = V + I (b) P = V × I (c) P = V ÷ I (d) P = I ÷ V
4. 4.📏 How many ohms make 1 kilo-ohm (kΩ)? (a) 1024 (b) 10 (c) 100 (d) 1000
5. 5.💡 An LED is joined to a 12 V battery with no resistor; the leg next to the flat edge of its rim goes to the − side. What happens? (a) lights up (b) does not light (c) may burn out
6. 6.🧩 Which component smooths a wobbly supply? (a) potentiometer (b) capacitor (c) LED (d) buzzer
7. 7.💡 Does it save or waste electricity to use LED lamps? (a) saves electricity (b) wastes electricity
8. 8.🔺 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
9. 9.🌈 A resistor has the colour bands violet, black, orange. What is its value (in ohms)?
10. 10.💡 Does it save or waste electricity to iron one shirt at a time? (a) saves electricity (b) wastes electricity
11. 11.True or false: the ammeter measures current. (a) False (b) True
12. 12.True or false: an LED boosts a small signal. (a) True (b) False
13. 13.🔺 A current of 2.5 A flows when 12.5 V is joined across a resistor. What is its resistance (in ohms)?
14. 14.What does a fuse do? (a) blows if current is high (b) stores a little charge (c) beeps for an alarm (d) smooths a wobbly supply
15. 15.📏 How many kilo-ohms (kΩ) is 5900 Ω? =
16. 16.🔺 A 5 V supply is joined across a 2 Ω resistor. What current flows (in amperes)? =
17. 17.🧩 Which part changes electrical energy into sound? (a) a diode (b) a resistor (c) a buzzer (d) a capacitor
18. 18.🌈 A resistor has the colour bands blue, black, orange. What is its value in kilo-ohms (kΩ)? =
19. 19.💡 An LED is joined to a 3 V battery through a 220 Ω resistor; the leg next to the flat edge of its rim goes to the − side. What happens? (a) may burn out (b) does not light (c) lights up
20. 20.💡 A red LED (it uses 2 V) is joined with a 200 Ω resistor to a 4 V supply. What current flows (in mA)?
21. 21.🧮 Resistors of 470 Ω, 20 Ω, 150 Ω and 100 Ω are joined in series. What is the total resistance (in ohms)?
22. 22.📏 Voltmeter or ammeter: which one measures voltage? (a) voltmeter (b) ammeter
23. 23.⚡ A device works on 5 V and takes 3 A. What is its power (in watts)? =
24. 24.💡 Why does an LED need a resistor in series? (a) to store charge (b) to make it brighter (c) to limit the current (d) to change its colour
25. 25.🧮 A 2.6 V battery is joined to 3 Ω and 10 Ω resistors in series. What current flows (in amperes)? =
26. 26.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) stays the same (b) gets bigger (c) becomes zero (d) gets smaller
27. 27.🔺 In the V-I-R triangle, how do we find I? (a) I = V ÷ R (b) I = V + R (c) I = R ÷ V (d) I = V × R
28. 28.🌈 Which band is read first on a resistor? (a) any band (b) the widest gap (c) the gold band (d) the one nearest an end
29. 29.📏 Which unit measures power? (a) ohm (Ω) (b) watt (W) (c) volt (V) (d) ampere (A)
30. 30.📏 How many amperes (A) is 1210 mA? =
31. 31.🧮 A 3.2 V battery is joined to 10 Ω and 6 Ω resistors in series. What current flows (in amperes)? =
32. 32.⚡ A home appliance on the 230 V mains takes 10 A. What is its power (in watts)?
33. 33.True or false: the voltmeter measures voltage. (a) False (b) True
34. 34.🧮 Three equal 75 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
35. 35.📏 How many kilowatts (kW) is 2100 W? =
36. 36.📏 In the water-pipe picture of a circuit, voltage is like … (a) the water pressure (b) the pipe colour (c) the tap handle (d) the water tank lid
37. 37.⚡ A 6 W device works on 24 V. What current does it take (in amperes)? =
38. 38.What does a thermistor do? (a) senses how hot it is (b) makes a beeping sound (c) smooths a wobbly supply (d) lets current go one way
39. 39.🧩 A capacitor in a circuit can … (a) store charge briefly (b) make light (c) measure heat (d) spin a wheel
40. 40.True or false: on an LED, the shorter leg is the anode (+). (a) False (b) True

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