Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 693 · 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 100 W filament bulb is swapped for a 15 W LED lamp that gives about the same light. Both would run for 3 hours. How many watt-hours (Wh) are saved?
2. 2.💡 What does LED stand for? (a) large electric dial (b) low energy device (c) light-emitting diode (d) light energy dial
3. 3.⚡ A device works on 3 V and takes 0.1 A. What is its power (in watts)? =
4. 4.🌈 A gold fourth band on a resistor means the value may be off by … (a) 5 % (b) 50 % (c) 25 % (d) 0 %
5. 5.Which of these is measured in watts (W)? (a) energy used each second (b) the flow of charge (c) the push of a cell (d) resistance
6. 6.⚡ Which formula gives electric power? (a) P = V + I (b) P = I ÷ V (c) P = V × I (d) P = V ÷ I
7. 7.🔺 A current of 2 A flows when 4 V is joined across a resistor. What is its resistance (in ohms)?
8. 8.💡 On an LED, is the leg by the flat edge the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
9. 9.📏 Which unit measures current? (a) volt (V) (b) watt (W) (c) ohm (Ω) (d) ampere (A)
10. 10.📏 Voltmeter or ammeter: which one measures voltage? (a) voltmeter (b) ammeter
11. 11.🔺 An 18 V supply is joined across a 6 Ω resistor. What current flows (in amperes)? =
12. 12.💡 On an LED, is the round-side leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
13. 13.What does a motor do? (a) senses how hot it is (b) makes things spin (c) smooths a wobbly supply (d) limits the current
14. 14.Which of these saves electricity? (a) switch off empty rooms (b) iron one shirt at a time (c) leave the TV on standby (d) run fans in empty rooms
15. 15.🔺 A current of 0.5 A flows through a 20 Ω resistor. What is the voltage across it (in volts)? =
16. 16.📏 How many kilo-ohms (kΩ) is 8300 Ω? =
17. 17.📏 In the water-pipe picture of a circuit, current is like … (a) the water pressure (b) the flow of water (c) a narrow pipe (d) the pipe colour
18. 18.True or false: a diode glows using little power. (a) False (b) True
19. 19.True or false: current is measured in ohms (Ω). (a) False (b) True
20. 20.🌈 Which band is read first on a resistor? (a) any band (b) the one nearest an end (c) the gold band (d) the widest gap
21. 21.🧩 A capacitor in a circuit can … (a) store charge briefly (b) make light (c) spin a wheel (d) measure heat
22. 22.🔺 A current of 25 mA flows when 6.25 V is joined across a resistor. What is its resistance (in ohms)?
23. 23.🔺 In the V-I-R triangle, how do we find I? (a) I = V + R (b) I = R ÷ V (c) I = V ÷ R (d) I = V × R
24. 24.📏 How many ohms (Ω) is 0.5 kΩ?
25. 25.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) gets smaller (b) gets bigger (c) becomes zero (d) stays the same
26. 26.🧮 Adding another resistor in series makes the total resistance … (a) stay the same (b) bigger (c) zero (d) smaller
27. 27.🌈 A resistor has the colour bands brown, grey, orange. What is its value in kilo-ohms (kΩ)? =
28. 28.🔺 In the V-I-R triangle, how do we find R? (a) R = I ÷ V (b) R = V ÷ I (c) R = V + I (d) R = V × I
29. 29.🔺 A current of 0.1 A flows when 0.2 V is joined across a resistor. What is its resistance (in ohms)?
30. 30.🧾 One “unit” on an electricity bill is … (a) 1 ampere (b) 1 kilowatt-hour (kWh) (c) 1 watt (d) 1 volt
31. 31.🌈 A resistor has the colour bands violet, violet, red. What is its value (in ohms)?
32. 32.🧮 Two resistors in parallel give a total that is … (a) more than either one (b) less than either one (c) always zero (d) their sum
33. 33.True or false: an LED smooths a wobbly supply. (a) False (b) True
34. 34.🔺 A current of 20 mA flows through a 150 Ω resistor. What is the voltage across it (in volts)? =
35. 35.What does a diode do? (a) makes things spin (b) stores a little charge (c) senses how bright it is (d) lets current go one way
36. 36.🔺 A 1.5 V supply is joined across a 15 Ω resistor. What current flows (in amperes)? =
37. 37.🔺 A current of 0.2 A flows through a 6 Ω resistor. What is the voltage across it (in volts)? =
38. 38.⚡ A home appliance on the 230 V mains takes 0.5 A. What is its power (in watts)?
39. 39.🔺 A current of 0.25 A flows when 1.25 V is joined across a resistor. What is its resistance (in ohms)?
40. 40.📏 In the water-pipe picture of a circuit, resistance is like … (a) a bigger tank (b) the water pressure (c) a narrow pipe (d) the flow of water

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