Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 657 · 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 3 V battery through a 1000 Ω resistor; its long leg goes to the + side and its short leg to the − side. What happens? (a) lights up (b) does not light (c) may burn out
2. 2.⚡ A device works on 12 V and takes 3 A. What is its power (in watts)? =
3. 3.🧾 A 100 W filament bulb is swapped for a 15 W LED lamp that gives about the same light. Both would run for 1 hour. How many watt-hours (Wh) are saved?
4. 4.True or false: the ammeter measures voltage. (a) False (b) True
5. 5.🔺 An 8 V supply is joined across a 400 Ω resistor. What current flows (in milliamperes, mA)?
6. 6.💡 On an LED, is the longer leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
7. 7.🔺 A current of 40 mA flows through a 250 Ω resistor. What is the voltage across it (in volts)? =
8. 8.🧮 Two equal 20 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
9. 9.🧾 A family uses 190 units of electricity in a month and each unit costs ₹7. What is the bill (in ₹)?
10. 10.🧮 Four equal 40 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
11. 11.🌈 A gold fourth band on a resistor means the value may be off by … (a) 25 % (b) 50 % (c) 5 % (d) 0 %
12. 12.🌈 A resistor has the colour bands yellow, grey, brown. What is its value (in ohms)?
13. 13.🔺 A 10 V supply is joined across a 20 Ω resistor. What current flows (in amperes)? =
14. 14.🔺 In the V-I-R triangle, how do we find R? (a) R = V × I (b) R = I ÷ V (c) R = V + I (d) R = V ÷ I
15. 15.True or false: to leave the TV on standby saves electricity. (a) True (b) False
16. 16.🧩 A capacitor in a circuit can … (a) make light (b) store charge briefly (c) measure heat (d) spin a wheel
17. 17.🧩 Which part changes electrical energy into movement? (a) a fuse (b) a motor (c) an LED (d) a resistor
18. 18.⚡ A device works on 1.5 V and takes 3 A. What is its power (in watts)? =
19. 19.🌈 A resistor has the colour bands orange, violet, orange. What is its value in kilo-ohms (kΩ)? =
20. 20.📏 Voltmeter or ammeter: which one is joined in series? (a) voltmeter (b) ammeter
21. 21.💡 Why does an LED need a resistor in series? (a) to store charge (b) to change its colour (c) to make it brighter (d) to limit the current
22. 22.⚡ A home appliance on the 230 V mains takes 5 A. What is its power (in watts)?
23. 23.🔺 In the V-I-R triangle, how do we find I? (a) I = V + R (b) I = R ÷ V (c) I = V ÷ R (d) I = V × R
24. 24.📏 Which unit measures the push of a cell? (a) volt (V) (b) ohm (Ω) (c) watt (W) (d) ampere (A)
25. 25.Which of these is measured in amperes (A)? (a) voltage (b) energy used each second (c) the flow of charge (d) the push of a cell
26. 26.🌈 Which band is read first on a resistor? (a) any band (b) the gold band (c) the widest gap (d) the one nearest an end
27. 27.🔺 A current of 10 mA flows when 4 V is joined across a resistor. What is its resistance (in ohms)?
28. 28.🧮 A 6 V battery is joined to 4 Ω and 8 Ω resistors in series. What current flows (in amperes)? =
29. 29.🧩 Which component glows using little power? (a) diode (b) capacitor (c) resistor (d) LED
30. 30.🔺 An 8.25 V supply is joined across a 330 Ω resistor. What current flows (in milliamperes, mA)?
31. 31.🌈 A resistor has the colour bands blue, blue, orange. What is its value in kilo-ohms (kΩ)? =
32. 32.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) becomes zero (b) gets smaller (c) gets bigger (d) stays the same
33. 33.📏 How many milliamperes (mA) is 1.67 A?
34. 34.🌈 A resistor has the colour bands grey, blue, orange. What is its value (in ohms)?
35. 35.🧮 Three equal 30 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
36. 36.True or false: the flow of charge is measured in amperes (A). (a) False (b) True
37. 37.True or false: power is measured in watts (W). (a) False (b) True
38. 38.🔺 A current of 2 A flows through a 12 Ω resistor. What is the voltage across it (in volts)? =
39. 39.True or false: the voltmeter measures current. (a) False (b) True
40. 40.True or false: a motor turns a fan or wheels. (a) True (b) False

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