Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 852 · 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.🧾 One “unit” on an electricity bill is … (a) 1 volt (b) 1 kilowatt-hour (kWh) (c) 1 watt (d) 1 ampere
2. 2.🌈 A resistor has the colour bands violet, green, red. What is its value (in ohms)?
3. 3.🔺 A current of 20 mA flows through a 200 Ω resistor. What is the voltage across it (in volts)? =
4. 4.True or false: energy used each second is measured in volts (V). (a) False (b) True
5. 5.🧮 Four equal 200 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
6. 6.🔺 A current of 20 mA flows when 4.4 V is joined across a resistor. What is its resistance (in ohms)?
7. 7.🔺 A current of 3 A flows through a 2 Ω resistor. What is the voltage across it (in volts)? =
8. 8.What does an LDR do? (a) is a resistance knob (b) senses how bright it is (c) makes things spin (d) senses how hot it is
9. 9.🔺 A 5 V supply is joined across a 500 Ω resistor. What current flows (in milliamperes, mA)?
10. 10.True or false: to iron one shirt at a time saves electricity. (a) True (b) False
11. 11.📏 In the water-pipe picture of a circuit, resistance is like … (a) a narrow pipe (b) the flow of water (c) a bigger tank (d) the water pressure
12. 12.What does a capacitor do? (a) makes a beeping sound (b) senses how hot it is (c) beeps for an alarm (d) stores a little charge
13. 13.🔺 A current of 2.5 A flows through a 4 Ω resistor. What is the voltage across it (in volts)? =
14. 14.🌈 A resistor has the colour bands white, yellow, orange. What is its value in kilo-ohms (kΩ)? =
15. 15.🔺 In the V-I-R triangle, how do we find I? (a) I = R ÷ V (b) I = V + R (c) I = V × R (d) I = V ÷ R
16. 16.⚡ A home appliance on the 230 V mains takes 2 A. What is its power (in watts)?
17. 17.🧮 Two equal 20 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
18. 18.🧾 A family uses 130 units of electricity in a month and each unit costs ₹5. What is the bill (in ₹)?
19. 19.True or false: to unplug idle chargers wastes electricity. (a) True (b) False
20. 20.🧩 Which component turns a fan or wheels? (a) potentiometer (b) LED (c) motor (d) transistor
21. 21.🧮 Adding another resistor in series makes the total resistance … (a) zero (b) stay the same (c) smaller (d) bigger
22. 22.True or false: a resistor senses how bright it is. (a) False (b) True
23. 23.💡 Does it save or waste electricity to use daylight to read? (a) wastes electricity (b) saves electricity
24. 24.🧮 A 150 Ω resistor is joined in series with two equal 40 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
25. 25.🌈 A resistor has the colour bands green, green, brown. What is its value (in ohms)?
26. 26.📏 How many kilowatts (kW) is 4050 W? =
27. 27.🔺 A current of 0.1 A flows through a 12 Ω resistor. What is the voltage across it (in volts)? =
28. 28.🔺 A current of 1 A flows when 8 V is joined across a resistor. What is its resistance (in ohms)?
29. 29.🔺 A 3.75 V supply is joined across a 15 Ω resistor. What current flows (in amperes)? =
30. 30.🔺 A 2 V supply is joined across a 200 Ω resistor. What current flows (in milliamperes, mA)?
31. 31.🌈 A resistor has the colour bands brown, red, brown. What is its value (in ohms)?
32. 32.What does a transistor do? (a) senses how bright it is (b) boosts a small signal (c) lets current go one way (d) glows using little power
33. 33.🧾 Which lamp gives the same light for the least power? (a) an oil lamp (b) a filament bulb (c) a candle (d) an LED lamp
34. 34.📏 Which unit measures energy used each second? (a) ohm (Ω) (b) ampere (A) (c) watt (W) (d) volt (V)
35. 35.🔺 A 3 V supply is joined across a 150 Ω resistor. What current flows (in milliamperes, mA)?
36. 36.🌈 Which band is read first on a resistor? (a) the widest gap (b) the gold band (c) any band (d) the one nearest an end
37. 37.True or false: a potentiometer is a resistance knob. (a) True (b) False
38. 38.Which of these saves electricity? (a) use old filament bulbs (b) leave fridge door open (c) switch off empty rooms (d) iron one shirt at a time
39. 39.⚡ Which formula gives electric power? (a) P = V ÷ I (b) P = V + I (c) P = I ÷ V (d) P = V × I
40. 40.💡 What happens if an LED is put in backwards? (a) it changes colour (b) it makes a sound (c) it does not light (d) it lights brighter

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