Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 151 · 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 7.5 V supply is joined across a 3 Ω resistor. What current flows (in amperes)? =
2. 2.🧩 Which component senses how bright it is? (a) fuse (b) transistor (c) LDR (d) resistor
3. 3.True or false: the voltmeter measures voltage. (a) True (b) False
4. 4.⚡ A home appliance on the 230 V mains takes 1.5 A. What is its power (in watts)?
5. 5.🧾 A family uses 150 units of electricity in a month and each unit costs ₹9. What is the bill (in ₹)?
6. 6.🧮 Two equal 1000 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
7. 7.🔺 In the V-I-R triangle, how do we find V? (a) V = I × R (b) V = R ÷ I (c) V = I + R (d) V = I ÷ R
8. 8.🧩 A capacitor in a circuit can … (a) measure heat (b) store charge briefly (c) make light (d) spin a wheel
9. 9.🔺 A current of 25 mA flows through a 500 Ω resistor. What is the voltage across it (in volts)? =
10. 10.🧩 Which component makes things spin? (a) thermistor (b) resistor (c) transistor (d) motor
11. 11.📏 Which unit measures voltage? (a) ampere (A) (b) volt (V) (c) ohm (Ω) (d) watt (W)
12. 12.🔺 A current of 0.1 A flows through a 2 Ω resistor. What is the voltage across it (in volts)? =
13. 13.⚡ A device works on 9 V and takes 0.25 A. What is its power (in watts)? =
14. 14.🌈 A resistor has the colour bands violet, orange, black. What is its value (in ohms)?
15. 15.📏 In the water-pipe picture of a circuit, voltage is like … (a) the pipe colour (b) the tap handle (c) the water pressure (d) the water tank lid
16. 16.🧩 Which component has coloured bands? (a) resistor (b) diode (c) LED (d) capacitor
17. 17.Which of these wastes electricity? (a) leave the TV on standby (b) set the AC to 24 °C (c) use LED lamps (d) use daylight to read
18. 18.🧾 One “unit” on an electricity bill is … (a) 1 kilowatt-hour (kWh) (b) 1 ampere (c) 1 watt (d) 1 volt
19. 19.🧮 A 3.6 V battery is joined to 10 Ω and 8 Ω resistors in series. What current flows (in amperes)? =
20. 20.🔺 A current of 3 A flows through a 15 Ω resistor. What is the voltage across it (in volts)? =
21. 21.💡 Does it save or waste electricity to iron one shirt at a time? (a) saves electricity (b) wastes electricity
22. 22.🔺 A 20 V supply is joined across a 500 Ω resistor. What current flows (in milliamperes, mA)?
23. 23.🧾 A family uses 40 units of electricity in a month and each unit costs ₹5. What is the bill (in ₹)?
24. 24.🧮 Two equal 50 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
25. 25.📏 How many kilo-ohms (kΩ) is 2500 Ω? =
26. 26.🧾 Which lamp gives the same light for the least power? (a) an LED lamp (b) an oil lamp (c) a filament bulb (d) a candle
27. 27.True or false: to iron one shirt at a time wastes electricity. (a) True (b) False
28. 28.True or false: the voltmeter is joined across a part. (a) False (b) True
29. 29.🧩 Which part changes electrical energy into sound? (a) a capacitor (b) a buzzer (c) a resistor (d) a diode
30. 30.🔺 A current of 0.2 A flows through a 15 Ω resistor. What is the voltage across it (in volts)? =
31. 31.🔺 A current of 2 A flows through a 4 Ω resistor. What is the voltage across it (in volts)? =
32. 32.🧮 A 10 Ω resistor is joined in series with two equal 470 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
33. 33.📏 How many milliamperes (mA) is 0.43 A?
34. 34.🧮 Two equal 330 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
35. 35.🔺 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
36. 36.🧮 Resistors of 470 Ω and 10 Ω are joined in series. What is the total resistance (in ohms)?
37. 37.📏 How many kilo-ohms (kΩ) is 6700 Ω? =
38. 38.⚡ Which formula gives electric power? (a) P = V + I (b) P = V ÷ I (c) P = I ÷ V (d) P = V × I
39. 39.🌈 A gold fourth band on a resistor means the value may be off by … (a) 5 % (b) 25 % (c) 50 % (d) 0 %
40. 40.🧾 A 60 W filament bulb is swapped for a 9 W LED lamp that gives about the same light. Both would run for 4 hours. How many watt-hours (Wh) are saved?

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