Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 680 · 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.📏 Voltmeter or ammeter: which one is joined across a part? (a) voltmeter (b) ammeter
2. 2.🔺 In the V-I-R triangle, how do we find R? (a) R = V × I (b) R = V + I (c) R = V ÷ I (d) R = I ÷ V
3. 3.🔍 Which is the odd one out? (a) iron one shirt at a time (b) leave fridge door open (c) run fans in empty rooms (d) use daylight to read
4. 4.🔺 A current of 1 A flows through a 5 Ω resistor. What is the voltage across it (in volts)? =
5. 5.🧩 Which component smooths a wobbly supply? (a) resistor (b) capacitor (c) transistor (d) LED
6. 6.📏 How many ohms (Ω) is 5.7 kΩ?
7. 7.🧮 A 1.8 V battery is joined to 10 Ω and 8 Ω resistors in series. What current flows (in amperes)? =
8. 8.💡 An LED is joined to a 5 V battery through a 220 Ω resistor; the leg next to the flat edge of its rim goes to the + side. What happens? (a) does not light (b) may burn out (c) lights up
9. 9.🌈 A resistor has the colour bands violet, black, orange. What is its value (in ohms)?
10. 10.True or false: on an LED, the round-side leg is the cathode (−). (a) True (b) False
11. 11.🔺 A current of 0.1 A flows through a 12 Ω resistor. What is the voltage across it (in volts)? =
12. 12.📏 In the water-pipe picture of a circuit, current is like … (a) the flow of water (b) the water pressure (c) a narrow pipe (d) the pipe colour
13. 13.🔺 A current of 1.5 A flows when 3 V is joined across a resistor. What is its resistance (in ohms)?
14. 14.🔺 A current of 40 mA flows when 8.8 V is joined across a resistor. What is its resistance (in ohms)?
15. 15.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) gets bigger (b) stays the same (c) gets smaller (d) becomes zero
16. 16.⚡ A home appliance on the 230 V mains takes 8 A. What is its power (in watts)?
17. 17.What does a diode do? (a) glows using little power (b) blows if current is high (c) lets current go one way (d) turns a fan or wheels
18. 18.Which of these is measured in ohms (Ω)? (a) current (b) the push of a cell (c) energy used each second (d) resistance
19. 19.🔺 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
20. 20.📏 Which unit measures energy used each second? (a) volt (V) (b) watt (W) (c) ampere (A) (d) ohm (Ω)
21. 21.🔺 In the V-I-R triangle, how do we find V? (a) V = I ÷ R (b) V = I + R (c) V = R ÷ I (d) V = I × R
22. 22.🔺 A 5 V supply is joined across a 10 Ω resistor. What current flows (in amperes)? =
23. 23.🧩 Which part changes electrical energy into movement? (a) a resistor (b) an LED (c) a motor (d) a fuse
24. 24.💡 A blue LED uses 3 V and should get 25 mA. It runs from a 5 V supply. What resistor (in ohms) is needed in series?
25. 25.True or false: the ammeter measures voltage. (a) False (b) True
26. 26.📏 How many kilo-ohms (kΩ) is 8100 Ω? =
27. 27.💡 A blue LED uses 3 V and should get 20 mA. It runs from a 6 V supply. What resistor (in ohms) is needed in series?
28. 28.🧩 A capacitor in a circuit can … (a) make light (b) spin a wheel (c) measure heat (d) store charge briefly
29. 29.🔺 A current of 20 mA flows when 2 V is joined across a resistor. What is its resistance (in ohms)?
30. 30.📏 How many amperes (A) is 2500 mA? =
31. 31.🧮 A 10 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)?
32. 32.🧾 A 75 W filament bulb is swapped for a 12 W LED lamp that gives about the same light. Both would run for 8 hours. How many watt-hours (Wh) are saved?
33. 33.⚡ A 4.5 W device works on 1.5 V. What current does it take (in amperes)? =
34. 34.🔺 A current of 10 mA flows when 2.2 V is joined across a resistor. What is its resistance (in ohms)?
35. 35.🔺 A current of 25 mA flows through a 500 Ω resistor. What is the voltage across it (in volts)? =
36. 36.🔍 Which is the odd one out? (a) use LED lamps (b) use daylight to read (c) use old filament bulbs (d) unplug idle chargers
37. 37.🧾 One “unit” on an electricity bill is … (a) 1 volt (b) 1 kilowatt-hour (kWh) (c) 1 ampere (d) 1 watt
38. 38.🔺 A 4 V supply is joined across a 400 Ω resistor. What current flows (in milliamperes, mA)?
39. 39.⚡ A device works on 6 V and takes 1.5 A. What is its power (in watts)? =
40. 40.True or false: to switch off empty rooms wastes electricity. (a) False (b) True

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