Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 164 · 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 resistor has the colour bands yellow, red, red. What is its value (in ohms)?
2. 2.🔺 A 22.5 V supply is joined across a 15 Ω resistor. What current flows (in amperes)? =
3. 3.🔺 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
4. 4.🧮 Two equal 220 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
5. 5.True or false: a resistor smooths a wobbly supply. (a) False (b) True
6. 6.🧩 Which part changes electrical energy into sound? (a) a diode (b) a capacitor (c) a resistor (d) a buzzer
7. 7.🧩 A capacitor in a circuit can … (a) spin a wheel (b) make light (c) store charge briefly (d) measure heat
8. 8.What does an LED do? (a) glows using little power (b) boosts a small signal (c) makes things spin (d) lets current go one way
9. 9.What does a capacitor do? (a) makes things spin (b) lets current go one way (c) limits the current (d) smooths a wobbly supply
10. 10.🧾 One “unit” on an electricity bill is … (a) 1 watt (b) 1 kilowatt-hour (kWh) (c) 1 volt (d) 1 ampere
11. 11.🔺 A 1.2 V supply is joined across a 120 Ω resistor. What current flows (in milliamperes, mA)?
12. 12.True or false: a thermistor stores a little charge. (a) True (b) False
13. 13.🔺 A current of 40 mA flows through a 100 Ω resistor. What is the voltage across it (in volts)? =
14. 14.🔺 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
15. 15.True or false: voltage is measured in volts (V). (a) True (b) False
16. 16.📏 Voltmeter or ammeter: which one measures voltage? (a) ammeter (b) voltmeter
17. 17.🧮 A 4 V battery is joined to 6 Ω and 10 Ω resistors in series. What current flows (in amperes)? =
18. 18.🧮 A 3 V battery is joined to 5 Ω and 10 Ω resistors in series. What current flows (in amperes)? =
19. 19.⚡ A device works on 12 V and takes 3 A. What is its power (in watts)? =
20. 20.📏 Which unit measures voltage? (a) watt (W) (b) volt (V) (c) ohm (Ω) (d) ampere (A)
21. 21.📏 In the water-pipe picture of a circuit, voltage is like … (a) the water pressure (b) the water tank lid (c) the tap handle (d) the pipe colour
22. 22.True or false: a potentiometer smooths a wobbly supply. (a) True (b) False
23. 23.🌈 In the resistor colour code, which number does orange stand for?
24. 24.🧩 Which component senses how bright it is? (a) potentiometer (b) buzzer (c) thermistor (d) LDR
25. 25.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) gets bigger (b) stays the same (c) becomes zero (d) gets smaller
26. 26.What does an LDR do? (a) makes things spin (b) is a resistance knob (c) blows if current is high (d) senses how bright it is
27. 27.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark an 880 Ω resistor? (a) grey-grey-black (b) grey-grey-brown (c) grey-grey-red (d) grey-white-brown
28. 28.Which of these is measured in watts (W)? (a) how much a part resists (b) the flow of charge (c) current (d) energy used each second
29. 29.🔍 Which is the odd one out? (a) unplug idle chargers (b) use daylight to read (c) switch off empty rooms (d) leave the TV on standby
30. 30.🧮 A 47 Ω resistor is joined in series with two equal 470 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
31. 31.🔺 A current of 3 A flows through a 2 Ω resistor. What is the voltage across it (in volts)? =
32. 32.🔺 A current of 50 mA flows when 23.5 V is joined across a resistor. What is its resistance (in ohms)?
33. 33.🧮 Three equal 75 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
34. 34.🔺 A current of 50 mA flows through a 150 Ω resistor. What is the voltage across it (in volts)? =
35. 35.True or false: the ammeter measures current. (a) False (b) True
36. 36.🔺 A current of 20 mA flows through a 330 Ω resistor. What is the voltage across it (in volts)? =
37. 37.🧮 Three equal 300 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
38. 38.💡 A red LED uses 2 V and should get 20 mA. It runs from a 12 V supply. What resistor (in ohms) is needed in series?
39. 39.🌈 A resistor has the colour bands green, brown, orange. What is its value in kilo-ohms (kΩ)? =
40. 40.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 7100 Ω resistor? (a) violet-brown-red (b) violet-brown-brown (c) brown-violet-red (d) violet-brown-orange

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