Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 233 · 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.💡 Why does an LED need a resistor in series? (a) to change its colour (b) to store charge (c) to make it brighter (d) to limit the current
2. 2.🧩 Which part changes electrical energy into sound? (a) a buzzer (b) a resistor (c) a diode (d) a capacitor
3. 3.📏 Which unit measures the flow of charge? (a) watt (W) (b) volt (V) (c) ohm (Ω) (d) ampere (A)
4. 4.🧩 Which component turns a fan or wheels? (a) motor (b) resistor (c) fuse (d) capacitor
5. 5.🔺 A current of 0.5 A flows when 3 V is joined across a resistor. What is its resistance (in ohms)?
6. 6.🔺 A current of 3 A flows through an 8 Ω resistor. What is the voltage across it (in volts)? =
7. 7.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) gets bigger (b) stays the same (c) becomes zero (d) gets smaller
8. 8.⚡ Which formula gives electric power? (a) P = V ÷ I (b) P = I ÷ V (c) P = V × I (d) P = V + I
9. 9.🧾 Which lamp gives the same light for the least power? (a) a filament bulb (b) an LED lamp (c) an oil lamp (d) a candle
10. 10.💡 What does LED stand for? (a) large electric dial (b) light-emitting diode (c) low energy device (d) light energy dial
11. 11.⚡ A 4.8 W device works on 24 V. What current does it take (in amperes)? =
12. 12.🔺 A current of 25 mA flows when 6.25 V is joined across a resistor. What is its resistance (in ohms)?
13. 13.Which of these wastes electricity? (a) set the AC to 24 °C (b) switch off empty rooms (c) run fans in empty rooms (d) use daylight to read
14. 14.🔍 Which is the odd one out? (a) use daylight to read (b) leave the TV on standby (c) unplug idle chargers (d) use LED lamps
15. 15.🔺 A current of 0.25 A flows through a 15 Ω resistor. What is the voltage across it (in volts)? =
16. 16.🌈 In the resistor colour code, which number does white stand for?
17. 17.🔺 In the V-I-R triangle, how do we find V? (a) V = I ÷ R (b) V = I + R (c) V = R ÷ I (d) V = I × R
18. 18.True or false: on an LED, the round-side leg is the cathode (−). (a) True (b) False
19. 19.True or false: on an LED, the shorter leg is the cathode (−). (a) True (b) False
20. 20.🔺 A current of 20 mA flows through a 220 Ω resistor. What is the voltage across it (in volts)? =
21. 21.🔍 Which is the odd one out? (a) set the AC to 24 °C (b) leave fridge door open (c) switch off empty rooms (d) unplug idle chargers
22. 22.True or false: a buzzer makes a beeping sound. (a) True (b) False
23. 23.🧮 Three equal 15 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
24. 24.🧮 Two equal 470 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
25. 25.⚡ A device works on 6 V and takes 0.1 A. What is its power (in watts)? =
26. 26.True or false: on an LED, the longer leg is the anode (+). (a) True (b) False
27. 27.🧾 A 1500 W appliance runs for 8 hours. How many units (kWh) of electricity does it use? =
28. 28.⚡ A home appliance on the 230 V mains takes 2 A. What is its power (in watts)?
29. 29.🔺 A 5 V supply is joined across a 250 Ω resistor. What current flows (in milliamperes, mA)?
30. 30.🧩 Which component stores a little charge? (a) resistor (b) capacitor (c) motor (d) diode
31. 31.🧮 Two resistors in parallel give a total that is … (a) less than either one (b) always zero (c) their sum (d) more than either one
32. 32.🧾 One “unit” on an electricity bill is … (a) 1 kilowatt-hour (kWh) (b) 1 watt (c) 1 ampere (d) 1 volt
33. 33.🧾 A family uses 110 units of electricity in a month and each unit costs ₹4. What is the bill (in ₹)?
34. 34.🧩 Which component senses how bright it is? (a) buzzer (b) LDR (c) diode (d) potentiometer
35. 35.⚡ A device works on 6 V and takes 1 A. What is its power (in watts)? =
36. 36.🔺 A current of 0.1 A flows when 0.3 V is joined across a resistor. What is its resistance (in ohms)?
37. 37.🔺 A current of 10 mA flows through a 330 Ω resistor. What is the voltage across it (in volts)? =
38. 38.⚡ Power tells us … (a) energy used each second (b) the length of a wire (c) the colour of light (d) the size of a cell
39. 39.True or false: an LDR senses how bright it is. (a) True (b) False
40. 40.🔺 In the V-I-R triangle, how do we find I? (a) I = V × R (b) I = V ÷ R (c) I = V + R (d) I = R ÷ V

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