Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 17 · 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 1 A flows when 6 V is joined across a resistor. What is its resistance (in ohms)?
2. 2.🧾 Which lamp gives the same light for the least power? (a) an oil lamp (b) an LED lamp (c) a filament bulb (d) a candle
3. 3.🧮 Two equal 50 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
4. 4.True or false: an LED blows if current is high. (a) True (b) False
5. 5.⚡ Which formula gives electric power? (a) P = V + I (b) P = V × I (c) P = V ÷ I (d) P = I ÷ V
6. 6.🔺 A 3.75 V supply is joined across a 15 Ω resistor. What current flows (in amperes)? =
7. 7.🔺 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
8. 8.True or false: a transistor boosts a small signal. (a) False (b) True
9. 9.🔺 A 7.5 V supply is joined across a 15 Ω resistor. What current flows (in amperes)? =
10. 10.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 25000 Ω resistor? (a) green-red-orange (b) red-green-red (c) red-green-yellow (d) red-green-orange
11. 11.🌈 A gold fourth band on a resistor means the value may be off by … (a) 50 % (b) 25 % (c) 0 % (d) 5 %
12. 12.📏 Which unit measures resistance? (a) ampere (A) (b) watt (W) (c) ohm (Ω) (d) volt (V)
13. 13.⚡ A 0.3 W device works on 3 V. What current does it take (in amperes)? =
14. 14.🌈 In the resistor colour code, which number does violet stand for?
15. 15.📏 How many kilowatts (kW) is 700 W? =
16. 16.🧩 Which component is a resistance knob? (a) motor (b) transistor (c) resistor (d) potentiometer
17. 17.🔺 An 8 V supply is joined across a 200 Ω resistor. What current flows (in milliamperes, mA)?
18. 18.🌈 A resistor has the colour bands red, violet, orange. What is its value in kilo-ohms (kΩ)? =
19. 19.🧩 Which component makes things spin? (a) buzzer (b) resistor (c) motor (d) capacitor
20. 20.⚡ Power tells us … (a) the colour of light (b) the length of a wire (c) the size of a cell (d) energy used each second
21. 21.Which of these saves electricity? (a) switch off empty rooms (b) leave fridge door open (c) iron one shirt at a time (d) leave the TV on standby
22. 22.💡 On an LED, is the shorter leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
23. 23.🔺 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
24. 24.🌈 A resistor has the colour bands brown, black, orange. What is its value (in ohms)?
25. 25.True or false: a resistor makes things spin. (a) False (b) True
26. 26.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 98 Ω resistor? (a) brown-grey-black (b) white-grey-brown (c) grey-white-black (d) white-grey-black
27. 27.Which of these is measured in watts (W)? (a) energy used each second (b) how much a part resists (c) resistance (d) the push of a cell
28. 28.🔺 A 10 V supply is joined across a 4 Ω resistor. What current flows (in amperes)? =
29. 29.Which of these is measured in amperes (A)? (a) the push of a cell (b) voltage (c) the flow of charge (d) power
30. 30.💡 On an LED, is the round-side leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
31. 31.⚡ A device works on 1.5 V and takes 3 A. What is its power (in watts)? =
32. 32.True or false: the voltmeter measures voltage. (a) True (b) False
33. 33.Which of these is measured in ohms (Ω)? (a) power (b) current (c) voltage (d) how much a part resists
34. 34.🔺 A current of 10 mA flows when 4.7 V is joined across a resistor. What is its resistance (in ohms)?
35. 35.🔺 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
36. 36.🔺 A current of 10 mA flows when 3.3 V is joined across a resistor. What is its resistance (in ohms)?
37. 37.🧩 A capacitor in a circuit can … (a) measure heat (b) make light (c) spin a wheel (d) store charge briefly
38. 38.📏 How many ohms make 1 kilo-ohm (kΩ)? (a) 10 (b) 1024 (c) 1000 (d) 100
39. 39.True or false: the voltmeter measures current. (a) True (b) False
40. 40.🌈 A resistor has the colour bands brown, violet, orange. What is its value (in ohms)?

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