Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 895 · 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.💡 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) does not light (b) may burn out (c) lights up
2. 2.💡 On an LED, is the round-side leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
3. 3.🔺 A current of 2 A flows through an 8 Ω resistor. What is the voltage across it (in volts)? =
4. 4.What does a capacitor do? (a) senses how bright it is (b) has coloured bands (c) stores a little charge (d) glows using little power
5. 5.📏 Which unit measures the push of a cell? (a) ampere (A) (b) watt (W) (c) ohm (Ω) (d) volt (V)
6. 6.🔺 A current of 20 mA flows through a 150 Ω resistor. What is the voltage across it (in volts)? =
7. 7.⚡ Power tells us … (a) the size of a cell (b) the colour of light (c) the length of a wire (d) energy used each second
8. 8.💡 Why does an LED need a resistor in series? (a) to limit the current (b) to change its colour (c) to store charge (d) to make it brighter
9. 9.💡 Does it save or waste electricity to use old filament bulbs? (a) wastes electricity (b) saves electricity
10. 10.💡 An LED is joined to a 6 V battery through a 220 Ω resistor; the leg next to the flat edge of its rim goes to the − side. What happens? (a) lights up (b) may burn out (c) does not light
11. 11.🧾 One “unit” on an electricity bill is … (a) 1 volt (b) 1 watt (c) 1 kilowatt-hour (kWh) (d) 1 ampere
12. 12.🧮 Adding another resistor in series makes the total resistance … (a) bigger (b) smaller (c) zero (d) stay the same
13. 13.💡 A blue LED uses 3 V and should get 20 mA. It runs from a 6 V supply. What resistor (in ohms) is needed in series?
14. 14.🧩 Which component turns a fan or wheels? (a) diode (b) potentiometer (c) resistor (d) motor
15. 15.⚡ A device works on 3 V and takes 0.5 A. What is its power (in watts)? =
16. 16.🌈 A resistor has the colour bands yellow, yellow, red. What is its value in kilo-ohms (kΩ)? =
17. 17.🔺 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
18. 18.🧮 A 3.5 V battery is joined to 3 Ω and 4 Ω resistors in series. What current flows (in amperes)? =
19. 19.⚡ A 0.6 W device works on 3 V. What current does it take (in amperes)? =
20. 20.⚡ A 24 W device works on 24 V. What current does it take (in amperes)? =
21. 21.🔺 In the V-I-R triangle, how do we find R? (a) R = I ÷ V (b) R = V + I (c) R = V × I (d) R = V ÷ I
22. 22.📏 Which unit measures power? (a) watt (W) (b) volt (V) (c) ampere (A) (d) ohm (Ω)
23. 23.📏 Voltmeter or ammeter: which one measures voltage? (a) voltmeter (b) ammeter
24. 24.🔺 A current of 25 mA flows through a 470 Ω resistor. What is the voltage across it (in volts)? =
25. 25.🧾 A family uses 140 units of electricity in a month and each unit costs ₹5. What is the bill (in ₹)?
26. 26.🌈 In the resistor colour code, which number does violet stand for?
27. 27.Which of these is measured in volts (V)? (a) the push of a cell (b) resistance (c) current (d) the flow of charge
28. 28.🧮 Resistors of 20 Ω, 150 Ω and 22 Ω are joined in series. What is the total resistance (in ohms)?
29. 29.🧮 Two equal 200 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
30. 30.🧩 Which part changes electrical energy into sound? (a) a resistor (b) a capacitor (c) a buzzer (d) a diode
31. 31.📏 How many milliamperes (mA) is 0.24 A?
32. 32.📏 Voltmeter or ammeter: which one is joined across a part? (a) voltmeter (b) ammeter
33. 33.🧩 Which component glows using little power? (a) capacitor (b) resistor (c) LED (d) fuse
34. 34.True or false: on an LED, the round-side leg is the anode (+). (a) True (b) False
35. 35.🧮 Two resistors in parallel give a total that is … (a) their sum (b) always zero (c) more than either one (d) less than either one
36. 36.⚡ A home appliance on the 230 V mains takes 10 A. What is its power (in watts)?
37. 37.⚡ A 4.5 W device works on 1.5 V. What current does it take (in amperes)? =
38. 38.📏 In the water-pipe picture of a circuit, voltage is like … (a) the pipe colour (b) the water pressure (c) the water tank lid (d) the tap handle
39. 39.True or false: to use old filament bulbs wastes electricity. (a) True (b) False
40. 40.🧩 Which component blows if current is high? (a) capacitor (b) fuse (c) resistor (d) transistor

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