Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 304 · 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 red LED uses 2 V and should get 10 mA. It runs from a 5 V supply. What resistor (in ohms) is needed in series?
2. 2.🌈 A resistor has the colour bands violet, green, red. What is its value in kilo-ohms (kΩ)? =
3. 3.🔺 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
4. 4.🧩 A capacitor in a circuit can … (a) make light (b) measure heat (c) store charge briefly (d) spin a wheel
5. 5.💡 On an LED, is the leg by the flat edge the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
6. 6.🧮 Adding another resistor in series makes the total resistance … (a) stay the same (b) zero (c) smaller (d) bigger
7. 7.⚡ A 0.5 W device works on 5 V. What current does it take (in amperes)? =
8. 8.🔺 A current of 0.1 A flows through a 10 Ω resistor. What is the voltage across it (in volts)? =
9. 9.🔺 A current of 20 mA flows through a 120 Ω resistor. What is the voltage across it (in volts)? =
10. 10.🧮 A 50 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)?
11. 11.🔺 A 16 V supply is joined across a 400 Ω resistor. What current flows (in milliamperes, mA)?
12. 12.⚡ A 27 W device works on 9 V. What current does it take (in amperes)? =
13. 13.💡 What happens if an LED is put in backwards? (a) it changes colour (b) it does not light (c) it makes a sound (d) it lights brighter
14. 14.🧾 A family uses 190 units of electricity in a month and each unit costs ₹8. What is the bill (in ₹)?
15. 15.🧮 Resistors of 150 Ω, 33 Ω, 33 Ω and 68 Ω are joined in series. What is the total resistance (in ohms)?
16. 16.True or false: a diode makes things spin. (a) True (b) False
17. 17.📏 In the water-pipe picture of a circuit, resistance is like … (a) a narrow pipe (b) the flow of water (c) the water pressure (d) a bigger tank
18. 18.🌈 A resistor has the colour bands red, blue, red. What is its value in kilo-ohms (kΩ)? =
19. 19.🔺 In the V-I-R triangle, how do we find V? (a) V = R ÷ I (b) V = I × R (c) V = I + R (d) V = I ÷ R
20. 20.⚡ Which formula gives electric power? (a) P = V + I (b) P = V × I (c) P = V ÷ I (d) P = I ÷ V
21. 21.💡 An LED is joined to a 6 V battery with no resistor; its long leg goes to the + side and its short leg to the − side. What happens? (a) may burn out (b) lights up (c) does not light
22. 22.What does a thermistor do? (a) senses how hot it is (b) blows if current is high (c) is a resistance knob (d) glows using little power
23. 23.🔺 A current of 10 mA flows when 2 V is joined across a resistor. What is its resistance (in ohms)?
24. 24.💡 On an LED, is the round-side leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
25. 25.🔺 A current of 0.25 A flows when 0.5 V is joined across a resistor. What is its resistance (in ohms)?
26. 26.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) gets bigger (b) becomes zero (c) stays the same (d) gets smaller
27. 27.🌈 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
28. 28.🔺 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
29. 29.🔺 A current of 0.25 A flows through a 10 Ω resistor. What is the voltage across it (in volts)? =
30. 30.📏 Which unit measures voltage? (a) volt (V) (b) watt (W) (c) ampere (A) (d) ohm (Ω)
31. 31.True or false: an LED is a resistance knob. (a) True (b) False
32. 32.🌈 A resistor has the colour bands white, grey, brown. What is its value (in ohms)?
33. 33.🧮 An 11 V battery is joined to 12 Ω and 10 Ω resistors in series. What current flows (in amperes)? =
34. 34.True or false: to use LED lamps saves electricity. (a) False (b) True
35. 35.🌈 In the resistor colour code, which number does blue stand for?
36. 36.🔺 A current of 40 mA flows when 6 V is joined across a resistor. What is its resistance (in ohms)?
37. 37.🔺 A current of 1.5 A flows through a 6 Ω resistor. What is the voltage across it (in volts)? =
38. 38.🧮 Three equal 60 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
39. 39.🔺 A current of 1 A flows through a 5 Ω resistor. What is the voltage across it (in volts)? =
40. 40.🔺 A current of 0.2 A flows when 1 V is joined across a resistor. What is its resistance (in ohms)?

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