Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 194 · 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 device works on 6 V and takes 0.25 A. What is its power (in watts)? =
2. 2.🔺 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
3. 3.🧮 Two equal 20 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
4. 4.🧩 Which part changes electrical energy into sound? (a) a resistor (b) a diode (c) a buzzer (d) a capacitor
5. 5.🧮 Resistors of 33 Ω, 220 Ω and 22 Ω are joined in series. What is the total resistance (in ohms)?
6. 6.True or false: current is measured in watts (W). (a) False (b) True
7. 7.🔺 A current of 10 mA flows when 4 V is joined across a resistor. What is its resistance (in ohms)?
8. 8.💡 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
9. 9.🔺 A current of 1.5 A flows through a 20 Ω resistor. What is the voltage across it (in volts)? =
10. 10.💡 What does LED stand for? (a) low energy device (b) light energy dial (c) large electric dial (d) light-emitting diode
11. 11.📏 Voltmeter or ammeter: which one measures current? (a) ammeter (b) voltmeter
12. 12.⚡ Power tells us … (a) the size of a cell (b) the length of a wire (c) the colour of light (d) energy used each second
13. 13.🔺 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
14. 14.True or false: on an LED, the longer leg is the anode (+). (a) True (b) False
15. 15.📏 Which unit measures the push of a cell? (a) ampere (A) (b) watt (W) (c) ohm (Ω) (d) volt (V)
16. 16.Which of these is measured in amperes (A)? (a) resistance (b) how much a part resists (c) current (d) energy used each second
17. 17.💡 What happens if an LED is put in backwards? (a) it changes colour (b) it makes a sound (c) it lights brighter (d) it does not light
18. 18.⚡ A device works on 3 V and takes 0.25 A. What is its power (in watts)? =
19. 19.🧮 A 1 V battery is joined to 2 Ω and 8 Ω resistors in series. What current flows (in amperes)? =
20. 20.💡 On an LED, is the leg by the flat edge the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
21. 21.⚡ A 12 W device works on 6 V. What current does it take (in amperes)? =
22. 22.🔺 A current of 40 mA flows through a 400 Ω resistor. What is the voltage across it (in volts)? =
23. 23.💡 A red LED (it uses 2 V) is joined with a 300 Ω resistor to a 5 V supply. What current flows (in mA)?
24. 24.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 60000 Ω resistor? (a) blue-black-red (b) blue-black-yellow (c) blue-black-orange (d) violet-blue-orange
25. 25.🧮 Resistors of 47 Ω, 33 Ω and 220 Ω are joined in series. What is the total resistance (in ohms)?
26. 26.⚡ A home appliance on the 230 V mains takes 1 A. What is its power (in watts)?
27. 27.🧮 Adding another resistor in series makes the total resistance … (a) zero (b) smaller (c) stay the same (d) bigger
28. 28.🔺 A current of 50 mA flows through a 150 Ω resistor. What is the voltage across it (in volts)? =
29. 29.🔺 A current of 25 mA flows through a 500 Ω resistor. What is the voltage across it (in volts)? =
30. 30.💡 On an LED, is the round-side leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
31. 31.Which of these wastes electricity? (a) unplug idle chargers (b) use daylight to read (c) set the AC to 24 °C (d) iron one shirt at a time
32. 32.🌈 In the resistor colour code, which number does yellow stand for?
33. 33.🔺 A 10 V supply is joined across a 20 Ω resistor. What current flows (in amperes)? =
34. 34.🧾 A family uses 110 units of electricity in a month and each unit costs ₹9. What is the bill (in ₹)?
35. 35.True or false: a transistor boosts a small signal. (a) True (b) False
36. 36.🔺 A 0.2 V supply is joined across a 2 Ω resistor. What current flows (in amperes)? =
37. 37.True or false: the voltmeter is joined in series. (a) True (b) False
38. 38.📏 Which unit measures how much a part resists? (a) volt (V) (b) ampere (A) (c) watt (W) (d) ohm (Ω)
39. 39.True or false: on an LED, the longer leg is the cathode (−). (a) False (b) True
40. 40.🔺 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

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