Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 187 · 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.True or false: the ammeter measures voltage. (a) True (b) False
2. 2.🧮 A 150 Ω resistor is joined in series with two equal 20 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
3. 3.🧮 A 4 V battery is joined to 2 Ω and 6 Ω resistors in series. What current flows (in amperes)? =
4. 4.📏 Voltmeter or ammeter: which one measures voltage? (a) voltmeter (b) ammeter
5. 5.Which of these is measured in ohms (Ω)? (a) the push of a cell (b) how much a part resists (c) current (d) power
6. 6.True or false: on an LED, the leg by the flat edge is the anode (+). (a) True (b) False
7. 7.True or false: on an LED, the round-side leg is the anode (+). (a) True (b) False
8. 8.🔺 A current of 40 mA flows when 20 V is joined across a resistor. What is its resistance (in ohms)?
9. 9.🧮 Adding another resistor in series makes the total resistance … (a) stay the same (b) bigger (c) zero (d) smaller
10. 10.📏 How many milliamperes (mA) is 0.37 A?
11. 11.⚡ Which formula gives electric power? (a) P = V × I (b) P = V ÷ I (c) P = V + I (d) P = I ÷ V
12. 12.🌈 A resistor has the colour bands orange, yellow, orange. What is its value (in ohms)?
13. 13.🧩 Which part changes electrical energy into sound? (a) a capacitor (b) a resistor (c) a diode (d) a buzzer
14. 14.💡 A red LED uses 2 V and should get 20 mA. It runs from a 12 V supply. What resistor (in ohms) is needed in series?
15. 15.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) gets bigger (b) stays the same (c) gets smaller (d) becomes zero
16. 16.🧾 A family uses 170 units of electricity in a month and each unit costs ₹4. What is the bill (in ₹)?
17. 17.💡 On an LED, is the shorter leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
18. 18.🧩 A capacitor in a circuit can … (a) make light (b) spin a wheel (c) measure heat (d) store charge briefly
19. 19.🔺 A 15 V supply is joined across a 10 Ω resistor. What current flows (in amperes)? =
20. 20.🧮 Two equal 470 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
21. 21.What does a transistor do? (a) smooths a wobbly supply (b) boosts a small signal (c) senses how bright it is (d) blows if current is high
22. 22.🔺 A current of 3 A flows when 30 V is joined across a resistor. What is its resistance (in ohms)?
23. 23.🔺 A current of 0.2 A flows through a 3 Ω resistor. What is the voltage across it (in volts)? =
24. 24.🔺 A current of 10 mA flows through a 200 Ω resistor. What is the voltage across it (in volts)? =
25. 25.🌈 A resistor has the colour bands violet, orange, black. What is its value (in ohms)?
26. 26.🧮 Two equal 10 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
27. 27.⚡ A device works on 12 V and takes 2 A. What is its power (in watts)? =
28. 28.📏 Voltmeter or ammeter: which one is joined in series? (a) ammeter (b) voltmeter
29. 29.🌈 A resistor has the colour bands grey, white, orange. What is its value in kilo-ohms (kΩ)? =
30. 30.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 6800 Ω resistor? (a) blue-grey-orange (b) blue-grey-brown (c) grey-blue-red (d) blue-grey-red
31. 31.🔺 A 4.5 V supply is joined across a 3 Ω resistor. What current flows (in amperes)? =
32. 32.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 5600 Ω resistor? (a) blue-green-red (b) green-blue-orange (c) green-blue-red (d) green-blue-brown
33. 33.🔍 Which is the odd one out? (a) use old filament bulbs (b) leave fridge door open (c) run fans in empty rooms (d) switch off empty rooms
34. 34.⚡ A home appliance on the 230 V mains takes 2 A. What is its power (in watts)?
35. 35.🧾 One “unit” on an electricity bill is … (a) 1 kilowatt-hour (kWh) (b) 1 ampere (c) 1 watt (d) 1 volt
36. 36.🌈 In the resistor colour code, which number does violet stand for?
37. 37.🔺 A current of 50 mA flows through a 250 Ω resistor. What is the voltage across it (in volts)? =
38. 38.💡 A red LED (it uses 2 V) is joined with a 200 Ω resistor to a 3 V supply. What current flows (in mA)?
39. 39.⚡ A 1 W device works on 5 V. What current does it take (in amperes)? =
40. 40.🔺 A 12 V supply is joined across an 8 Ω resistor. What current flows (in amperes)? =

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