Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 33 · 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.📏 How many milliamperes (mA) is 1.84 A?
2. 2.💡 On an LED, is the longer leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
3. 3.What does an LDR do? (a) limits the current (b) glows using little power (c) lets current go one way (d) senses how bright it is
4. 4.📏 Which unit measures the push of a cell? (a) ampere (A) (b) volt (V) (c) ohm (Ω) (d) watt (W)
5. 5.🌈 A resistor has the colour bands blue, red, brown. What is its value (in ohms)?
6. 6.🌈 A resistor has the colour bands yellow, orange, black. What is its value (in ohms)?
7. 7.🌈 In the resistor colour code, which number does brown stand for?
8. 8.🧮 Three equal 30 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
9. 9.📏 Voltmeter or ammeter: which one is joined in series? (a) ammeter (b) voltmeter
10. 10.🔺 A 10 V supply is joined across a 500 Ω resistor. What current flows (in milliamperes, mA)?
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.🔺 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
13. 13.🔺 A current of 10 mA flows through a 100 Ω resistor. What is the voltage across it (in volts)? =
14. 14.🧮 Resistors of 33 Ω and 47 Ω are joined in series. What is the total resistance (in ohms)?
15. 15.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 94 Ω resistor? (a) yellow-white-black (b) white-yellow-brown (c) brown-yellow-black (d) white-yellow-black
16. 16.💡 An LED is joined to a 3 V battery through a 470 Ω 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
17. 17.⚡ Which formula gives electric power? (a) P = V × I (b) P = V + I (c) P = V ÷ I (d) P = I ÷ V
18. 18.🧾 A 100 W filament bulb is swapped for a 15 W LED lamp that gives about the same light. Both would run for 9 hours. How many watt-hours (Wh) are saved?
19. 19.⚡ A home appliance on the 230 V mains takes 10 A. What is its power (in watts)?
20. 20.🧩 Which part changes electrical energy into movement? (a) a motor (b) a resistor (c) an LED (d) a fuse
21. 21.Which of these is measured in amperes (A)? (a) power (b) resistance (c) the flow of charge (d) how much a part resists
22. 22.⚡ Power tells us … (a) the size of a cell (b) the length of a wire (c) the colour of light (d) energy used each second
23. 23.🔺 A 9 V supply is joined across a 3 Ω resistor. What current flows (in amperes)? =
24. 24.🧾 A 2000 W appliance runs for 8 hours. How many units (kWh) of electricity does it use? =
25. 25.📏 In the water-pipe picture of a circuit, current is like … (a) the water pressure (b) the flow of water (c) the pipe colour (d) a narrow pipe
26. 26.🌈 A resistor has the colour bands green, orange, orange. What is its value in kilo-ohms (kΩ)? =
27. 27.🔺 A 20 V supply is joined across a 10 Ω resistor. What current flows (in amperes)? =
28. 28.🧾 A 250 W appliance runs for 4 hours. How many units (kWh) of electricity does it use? =
29. 29.What does a thermistor do? (a) senses how hot it is (b) stores a little charge (c) has coloured bands (d) blows if current is high
30. 30.What does a capacitor do? (a) makes a beeping sound (b) beeps for an alarm (c) has coloured bands (d) stores a little charge
31. 31.True or false: energy used each second is measured in amperes (A). (a) True (b) False
32. 32.📏 How many kilowatts (kW) is 4700 W? =
33. 33.📏 How many kilo-ohms (kΩ) is 6600 Ω? =
34. 34.⚡ A device works on 12 V and takes 1.5 A. What is its power (in watts)? =
35. 35.📏 In the water-pipe picture of a circuit, resistance is like … (a) the flow of water (b) a narrow pipe (c) a bigger tank (d) the water pressure
36. 36.🔺 A 2.5 V supply is joined across a 5 Ω resistor. What current flows (in amperes)? =
37. 37.💡 On an LED, is the leg by the flat edge the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
38. 38.⚡ A device works on 3 V and takes 0.5 A. What is its power (in watts)? =
39. 39.True or false: an LDR limits the current. (a) True (b) False
40. 40.🧩 Which component beeps for an alarm? (a) thermistor (b) buzzer (c) capacitor (d) transistor

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