Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 837 · 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 current of 3 A flows through a 3 Ω resistor. What is the voltage across it (in volts)? =
2. 2.🌈 Which band is read first on a resistor? (a) the widest gap (b) the gold band (c) the one nearest an end (d) any band
3. 3.True or false: to unplug idle chargers saves electricity. (a) False (b) True
4. 4.🔺 A current of 0.5 A flows through a 12 Ω resistor. What is the voltage across it (in volts)? =
5. 5.Which of these saves electricity? (a) leave the TV on standby (b) close the fridge quickly (c) iron one shirt at a time (d) run fans in empty rooms
6. 6.🔺 A current of 20 mA flows through a 500 Ω resistor. What is the voltage across it (in volts)? =
7. 7.💡 Why does an LED need a resistor in series? (a) to store charge (b) to limit the current (c) to change its colour (d) to make it brighter
8. 8.🧮 Two equal 220 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
9. 9.🔺 A current of 0.25 A flows through a 6 Ω resistor. What is the voltage across it (in volts)? =
10. 10.📏 Voltmeter or ammeter: which one is joined across a part? (a) ammeter (b) voltmeter
11. 11.🔺 In the V-I-R triangle, how do we find V? (a) V = I ÷ R (b) V = I × R (c) V = I + R (d) V = R ÷ I
12. 12.🧮 Two equal 40 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
13. 13.🔍 Which is the odd one out? (a) leave the TV on standby (b) set the AC to 24 °C (c) switch off empty rooms (d) use LED lamps
14. 14.📏 How many milliamperes (mA) is 2.11 A?
15. 15.⚡ A home appliance on the 230 V mains takes 1.5 A. What is its power (in watts)?
16. 16.💡 What happens if an LED is put in backwards? (a) it lights brighter (b) it makes a sound (c) it does not light (d) it changes colour
17. 17.Which of these is measured in watts (W)? (a) the push of a cell (b) the flow of charge (c) power (d) current
18. 18.🔺 A current of 10 mA flows when 2.2 V is joined across a resistor. What is its resistance (in ohms)?
19. 19.📏 How many amperes (A) is 2900 mA? =
20. 20.⚡ A 12 W device works on 12 V. What current does it take (in amperes)? =
21. 21.📏 Which unit measures current? (a) ohm (Ω) (b) volt (V) (c) watt (W) (d) ampere (A)
22. 22.🔺 A current of 3 A flows when 60 V is joined across a resistor. What is its resistance (in ohms)?
23. 23.🧾 A family uses 120 units of electricity in a month and each unit costs ₹9. What is the bill (in ₹)?
24. 24.💡 A blue LED uses 3 V and should get 25 mA. It runs from a 9 V supply. What resistor (in ohms) is needed in series?
25. 25.True or false: the flow of charge is measured in amperes (A). (a) False (b) True
26. 26.🌈 In the resistor colour code, which number does green stand for?
27. 27.🧮 Five equal 50 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
28. 28.🔺 A current of 1 A flows through a 3 Ω resistor. What is the voltage across it (in volts)? =
29. 29.🔺 A 2 V supply is joined across a 200 Ω resistor. What current flows (in milliamperes, mA)?
30. 30.🔺 A 15 V supply is joined across a 300 Ω resistor. What current flows (in milliamperes, mA)?
31. 31.🧩 Which component is a resistance knob? (a) capacitor (b) transistor (c) potentiometer (d) thermistor
32. 32.⚡ A 4.5 W device works on 9 V. What current does it take (in amperes)? =
33. 33.🔺 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
34. 34.🧮 Resistors of 220 Ω, 22 Ω, 470 Ω and 50 Ω are joined in series. What is the total resistance (in ohms)?
35. 35.💡 On an LED, is the round-side leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
36. 36.🔺 A current of 0.1 A flows through a 2 Ω resistor. What is the voltage across it (in volts)? =
37. 37.🔺 A current of 1 A flows through a 6 Ω resistor. What is the voltage across it (in volts)? =
38. 38.🌈 A resistor has the colour bands red, orange, red. What is its value in kilo-ohms (kΩ)? =
39. 39.🔺 In the V-I-R triangle, how do we find R? (a) R = V ÷ I (b) R = V + I (c) R = I ÷ V (d) R = V × I
40. 40.True or false: on an LED, the leg by the flat edge is the cathode (−). (a) True (b) False

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