Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 610 · 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.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 74000 Ω resistor? (a) violet-yellow-orange (b) yellow-violet-orange (c) violet-yellow-yellow (d) violet-yellow-red
2. 2.🔺 A current of 3 A flows through a 20 Ω resistor. What is the voltage across it (in volts)? =
3. 3.🔺 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
4. 4.What does a potentiometer do? (a) is a resistance knob (b) senses how hot it is (c) beeps for an alarm (d) limits the current
5. 5.🌈 A resistor has the colour bands brown, yellow, orange. What is its value (in ohms)?
6. 6.💡 A red LED uses 2 V and should get 25 mA. It runs from a 6 V supply. What resistor (in ohms) is needed in series?
7. 7.💡 On an LED, is the leg by the flat edge the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
8. 8.🔍 Which is the odd one out? (a) use LED lamps (b) use daylight to read (c) leave the TV on standby (d) switch off empty rooms
9. 9.⚡ A home appliance on the 230 V mains takes 0.5 A. What is its power (in watts)?
10. 10.🔺 A current of 20 mA flows through a 150 Ω resistor. What is the voltage across it (in volts)? =
11. 11.🔺 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
12. 12.🌈 Which band is read first on a resistor? (a) the gold band (b) the widest gap (c) the one nearest an end (d) any band
13. 13.📏 Voltmeter or ammeter: which one is joined across a part? (a) ammeter (b) voltmeter
14. 14.Which of these saves electricity? (a) leave the TV on standby (b) close the fridge quickly (c) use old filament bulbs (d) iron one shirt at a time
15. 15.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) stays the same (b) becomes zero (c) gets smaller (d) gets bigger
16. 16.⚡ A device works on 3 V and takes 0.2 A. What is its power (in watts)? =
17. 17.🧩 Which component stores a little charge? (a) LDR (b) potentiometer (c) diode (d) capacitor
18. 18.💡 What does LED stand for? (a) large electric dial (b) low energy device (c) light energy dial (d) light-emitting diode
19. 19.💡 An LED is joined to a 3 V battery through a 220 Ω resistor; its long leg goes to the + side and its short leg to the − side. What happens? (a) may burn out (b) does not light (c) lights up
20. 20.🌈 A resistor has the colour bands grey, grey, brown. What is its value (in ohms)?
21. 21.📏 Which unit measures voltage? (a) ohm (Ω) (b) watt (W) (c) volt (V) (d) ampere (A)
22. 22.🧮 Five equal 100 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
23. 23.🧾 A 250 W appliance runs for 6 hours. How many units (kWh) of electricity does it use? =
24. 24.True or false: to close the fridge quickly wastes electricity. (a) False (b) True
25. 25.What does an LED do? (a) blows if current is high (b) smooths a wobbly supply (c) glows using little power (d) boosts a small signal
26. 26.Which of these is measured in volts (V)? (a) voltage (b) resistance (c) the flow of charge (d) current
27. 27.⚡ Power tells us … (a) the size of a cell (b) energy used each second (c) the length of a wire (d) the colour of light
28. 28.📏 Which unit measures current? (a) ohm (Ω) (b) volt (V) (c) watt (W) (d) ampere (A)
29. 29.⚡ A 12 W device works on 12 V. What current does it take (in amperes)? =
30. 30.🔺 A current of 40 mA flows when 8 V is joined across a resistor. What is its resistance (in ohms)?
31. 31.🧩 Which part changes electrical energy into sound? (a) a diode (b) a resistor (c) a capacitor (d) a buzzer
32. 32.What does a transistor do? (a) turns a fan or wheels (b) boosts a small signal (c) glows using little power (d) makes a beeping sound
33. 33.🧮 Adding another resistor in series makes the total resistance … (a) bigger (b) smaller (c) stay the same (d) zero
34. 34.Which of these is measured in amperes (A)? (a) voltage (b) current (c) resistance (d) the push of a cell
35. 35.💡 An LED is joined to a 9 V battery with no resistor; its long leg goes to the + side and its short leg to the − side. What happens? (a) may burn out (b) does not light (c) lights up
36. 36.📏 Which unit measures the flow of charge? (a) watt (W) (b) volt (V) (c) ampere (A) (d) ohm (Ω)
37. 37.🔺 In the V-I-R triangle, how do we find I? (a) I = V × R (b) I = V + R (c) I = V ÷ R (d) I = R ÷ V
38. 38.💡 An LED is joined to a 9 V battery through a 330 Ω resistor; its long leg goes to the + side and its short leg to the − side. What happens? (a) may burn out (b) lights up (c) does not light
39. 39.⚡ Which formula gives electric power? (a) P = V × I (b) P = V ÷ I (c) P = I ÷ V (d) P = V + I
40. 40.🔺 A current of 1 A flows through an 8 Ω resistor. What is the voltage across it (in volts)? =

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