Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 58 · 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: voltage is measured in watts (W). (a) True (b) False
2. 2.True or false: how much a part resists is measured in watts (W). (a) True (b) False
3. 3.🌈 In the resistor colour code, which number does orange stand for?
4. 4.🔺 A 3 V supply is joined across a 120 Ω resistor. What current flows (in milliamperes, mA)?
5. 5.🌈 Which band is read first on a resistor? (a) the one nearest an end (b) the widest gap (c) the gold band (d) any band
6. 6.🔺 A current of 0.25 A flows through a 3 Ω resistor. What is the voltage across it (in volts)? =
7. 7.True or false: the flow of charge is measured in volts (V). (a) False (b) True
8. 8.🔺 A current of 25 mA flows through a 500 Ω resistor. What is the voltage across it (in volts)? =
9. 9.🔺 A current of 25 mA flows through a 120 Ω resistor. What is the voltage across it (in volts)? =
10. 10.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) gets bigger (b) gets smaller (c) becomes zero (d) stays the same
11. 11.🔺 A current of 2.5 A flows through a 6 Ω resistor. What is the voltage across it (in volts)? =
12. 12.🧩 Which part changes electrical energy into movement? (a) an LED (b) a fuse (c) a resistor (d) a motor
13. 13.Which of these is measured in amperes (A)? (a) energy used each second (b) resistance (c) the flow of charge (d) voltage
14. 14.🔺 A current of 0.1 A flows when 2 V is joined across a resistor. What is its resistance (in ohms)?
15. 15.⚡ Which formula gives electric power? (a) P = V ÷ I (b) P = V + I (c) P = V × I (d) P = I ÷ V
16. 16.⚡ Power tells us … (a) the colour of light (b) the size of a cell (c) the length of a wire (d) energy used each second
17. 17.💡 On an LED, is the shorter leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
18. 18.True or false: the voltmeter is joined in series. (a) False (b) True
19. 19.🔺 In the V-I-R triangle, how do we find V? (a) V = I ÷ R (b) V = R ÷ I (c) V = I + R (d) V = I × R
20. 20.🧾 A 40 W filament bulb is swapped for a 6 W LED lamp that gives about the same light. Both would run for 3 hours. How many watt-hours (Wh) are saved?
21. 21.📏 How many amperes (A) is 690 mA? =
22. 22.⚡ A 0.375 W device works on 1.5 V. What current does it take (in amperes)? =
23. 23.🧾 A family uses 110 units of electricity in a month and each unit costs ₹4. What is the bill (in ₹)?
24. 24.🔺 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
25. 25.🌈 A resistor has the colour bands white, red, red. What is its value (in ohms)?
26. 26.🧮 A 20 Ω resistor is joined in series with two equal 330 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
27. 27.📏 Which unit measures voltage? (a) ohm (Ω) (b) volt (V) (c) watt (W) (d) ampere (A)
28. 28.Which of these saves electricity? (a) run fans in empty rooms (b) leave fridge door open (c) iron one shirt at a time (d) use LED lamps
29. 29.🧮 A 470 Ω resistor is joined in series with two equal 1000 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
30. 30.🧾 A 40 W filament bulb is swapped for a 6 W LED lamp that gives about the same light. Both would run for 6 hours. How many watt-hours (Wh) are saved?
31. 31.📏 Voltmeter or ammeter: which one is joined across a part? (a) ammeter (b) voltmeter
32. 32.True or false: to run fans in empty rooms saves electricity. (a) False (b) True
33. 33.💡 Does it save or waste electricity to use LED lamps? (a) saves electricity (b) wastes electricity
34. 34.🔍 Which is the odd one out? (a) leave fridge door open (b) leave the TV on standby (c) run fans in empty rooms (d) close the fridge quickly
35. 35.True or false: on an LED, the leg by the flat edge is the cathode (−). (a) False (b) True
36. 36.🧮 Resistors of 50 Ω and 100 Ω are joined in series. What is the total resistance (in ohms)?
37. 37.📏 How many kilo-ohms (kΩ) is 2900 Ω? =
38. 38.🧮 A 3.25 V battery is joined to 8 Ω and 5 Ω resistors in series. What current flows (in amperes)? =
39. 39.🌈 A resistor has the colour bands red, blue, orange. What is its value (in ohms)?
40. 40.💡 A blue LED uses 3 V and should get 10 mA. It runs from a 5 V supply. What resistor (in ohms) is needed in series?

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