Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 76 · 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.⚡ Power tells us … (a) the colour of light (b) the size of a cell (c) energy used each second (d) the length of a wire
2. 2.True or false: to run fans in empty rooms saves electricity. (a) True (b) False
3. 3.💡 A blue LED uses 3 V and should get 10 mA. It runs from a 6 V supply. What resistor (in ohms) is needed in series?
4. 4.What does a transistor do? (a) has coloured bands (b) glows using little power (c) senses how hot it is (d) boosts a small signal
5. 5.💡 Why does an LED need a resistor in series? (a) to limit the current (b) to store charge (c) to make it brighter (d) to change its colour
6. 6.🧾 A 100 W filament bulb is swapped for a 15 W LED lamp that gives about the same light. Both would run for 4 hours. How many watt-hours (Wh) are saved?
7. 7.🔺 A current of 2.5 A flows through a 4 Ω resistor. What is the voltage across it (in volts)? =
8. 8.True or false: the ammeter measures voltage. (a) True (b) False
9. 9.🌈 In the resistor colour code, which number does black stand for?
10. 10.🔺 A 1 V supply is joined across a 4 Ω resistor. What current flows (in amperes)? =
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.⚡ A 1 W device works on 5 V. What current does it take (in amperes)? =
13. 13.🔺 A current of 25 mA flows through a 400 Ω resistor. What is the voltage across it (in volts)? =
14. 14.True or false: the flow of charge is measured in amperes (A). (a) True (b) False
15. 15.⚡ A 0.15 W device works on 1.5 V. What current does it take (in amperes)? =
16. 16.🧮 A 3.6 V battery is joined to 12 Ω and 6 Ω resistors in series. What current flows (in amperes)? =
17. 17.🌈 In the resistor colour code, which number does grey stand for?
18. 18.⚡ Which formula gives electric power? (a) P = I ÷ V (b) P = V × I (c) P = V + I (d) P = V ÷ I
19. 19.True or false: power is measured in ohms (Ω). (a) True (b) False
20. 20.🔺 A current of 3 A flows through a 20 Ω resistor. What is the voltage across it (in volts)? =
21. 21.🌈 In the resistor colour code, which number does yellow stand for?
22. 22.🔺 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
23. 23.🔺 A current of 20 mA flows through a 250 Ω resistor. What is the voltage across it (in volts)? =
24. 24.True or false: a resistor stores a little charge. (a) True (b) False
25. 25.🧮 A 1.3 V battery is joined to 3 Ω and 10 Ω resistors in series. What current flows (in amperes)? =
26. 26.💡 A blue LED uses 3 V and should get 20 mA. It runs from a 12 V supply. What resistor (in ohms) is needed in series?
27. 27.📏 How many kilowatts (kW) is 1850 W? =
28. 28.🔺 A current of 50 mA flows through a 500 Ω resistor. What is the voltage across it (in volts)? =
29. 29.🧩 Which component lets current go one way? (a) diode (b) motor (c) capacitor (d) LDR
30. 30.True or false: energy used each second is measured in volts (V). (a) True (b) False
31. 31.🧮 Resistors of 33 Ω and 47 Ω are joined in series. What is the total resistance (in ohms)?
32. 32.🔺 A current of 20 mA flows through a 120 Ω resistor. What is the voltage across it (in volts)? =
33. 33.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark an 80 Ω resistor? (a) grey-black-black (b) grey-black-brown (c) white-black-black (d) white-grey-black
34. 34.📏 How many kilo-ohms (kΩ) is 2900 Ω? =
35. 35.🌈 Which band is read first on a resistor? (a) the widest gap (b) any band (c) the one nearest an end (d) the gold band
36. 36.🔺 A 24 V supply is joined across a 12 Ω resistor. What current flows (in amperes)? =
37. 37.True or false: a buzzer makes a beeping sound. (a) False (b) True
38. 38.True or false: an LED is a resistance knob. (a) True (b) False
39. 39.What does a buzzer do? (a) glows using little power (b) makes a beeping sound (c) makes things spin (d) smooths a wobbly supply
40. 40.🌈 In the resistor colour code, which number does brown stand for?

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