Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 654 · 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.True or false: the voltmeter measures current. (a) False (b) True
2. 2.🔺 A 6 V supply is joined across a 300 Ω resistor. What current flows (in milliamperes, mA)?
3. 3.💡 Does it save or waste electricity to use LED lamps? (a) wastes electricity (b) saves electricity
4. 4.🧾 A 40 W filament bulb is swapped for a 6 W LED lamp that gives about the same light. Both would run for 9 hours. How many watt-hours (Wh) are saved?
5. 5.🔺 In the V-I-R triangle, how do we find I? (a) I = V ÷ R (b) I = V × R (c) I = R ÷ V (d) I = V + R
6. 6.True or false: on an LED, the round-side leg is the anode (+). (a) False (b) True
7. 7.🔺 A current of 0.2 A flows through a 12 Ω resistor. What is the voltage across it (in volts)? =
8. 8.⚡ Which formula gives electric power? (a) P = V ÷ I (b) P = I ÷ V (c) P = V + I (d) P = V × I
9. 9.True or false: the push of a cell is measured in amperes (A). (a) True (b) False
10. 10.⚡ Power tells us … (a) the size of a cell (b) energy used each second (c) the colour of light (d) the length of a wire
11. 11.💡 What happens if an LED is put in backwards? (a) it lights brighter (b) it makes a sound (c) it does not light (d) it changes colour
12. 12.Which of these saves electricity? (a) use LED lamps (b) leave fridge door open (c) iron one shirt at a time (d) use old filament bulbs
13. 13.⚡ A device works on 3 V and takes 3 A. What is its power (in watts)? =
14. 14.🧩 Which component is a resistance knob? (a) capacitor (b) diode (c) resistor (d) potentiometer
15. 15.🔺 A 3 V supply is joined across a 6 Ω resistor. What current flows (in amperes)? =
16. 16.True or false: current is measured in watts (W). (a) True (b) False
17. 17.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) gets bigger (b) becomes zero (c) stays the same (d) gets smaller
18. 18.🔍 Which is the odd one out? (a) use LED lamps (b) use old filament bulbs (c) leave fridge door open (d) run fans in empty rooms
19. 19.🌈 A resistor has the colour bands yellow, grey, brown. What is its value (in ohms)?
20. 20.True or false: a motor makes things spin. (a) False (b) True
21. 21.True or false: resistance is measured in amperes (A). (a) False (b) True
22. 22.🌈 A resistor has the colour bands red, orange, yellow. What is its value in kilo-ohms (kΩ)? =
23. 23.💡 Does it save or waste electricity to close the fridge quickly? (a) wastes electricity (b) saves electricity
24. 24.🔺 A current of 2.5 A flows through a 10 Ω resistor. What is the voltage across it (in volts)? =
25. 25.Which of these is measured in watts (W)? (a) the flow of charge (b) current (c) power (d) how much a part resists
26. 26.⚡ A device works on 1.5 V and takes 0.2 A. What is its power (in watts)? =
27. 27.⚡ A home appliance on the 230 V mains takes 0.5 A. What is its power (in watts)?
28. 28.Which of these saves electricity? (a) use daylight to read (b) leave fridge door open (c) use old filament bulbs (d) run fans in empty rooms
29. 29.⚡ A device works on 12 V and takes 3 A. What is its power (in watts)? =
30. 30.Which of these saves electricity? (a) run fans in empty rooms (b) switch off empty rooms (c) use old filament bulbs (d) leave the TV on standby
31. 31.🔺 A current of 0.25 A flows through a 6 Ω resistor. What is the voltage across it (in volts)? =
32. 32.💡 An LED is joined to a 6 V battery through a 1000 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
33. 33.💡 A blue LED uses 3 V and should get 10 mA. It runs from a 5 V supply. What resistor (in ohms) is needed in series?
34. 34.🔺 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
35. 35.True or false: the voltmeter is joined across a part. (a) False (b) True
36. 36.🔺 A 2 V supply is joined across a 2 Ω resistor. What current flows (in amperes)? =
37. 37.🌈 A resistor has the colour bands red, black, yellow. What is its value in kilo-ohms (kΩ)? =
38. 38.🌈 Which band is read first on a resistor? (a) any band (b) the gold band (c) the one nearest an end (d) the widest gap
39. 39.🧾 A 60 W filament bulb is swapped for a 9 W LED lamp that gives about the same light. Both would run for 4 hours. How many watt-hours (Wh) are saved?
40. 40.🧩 Which part changes electrical energy into sound? (a) a resistor (b) a diode (c) a buzzer (d) a capacitor

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