Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 293 · 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 gold fourth band on a resistor means the value may be off by … (a) 5 % (b) 25 % (c) 0 % (d) 50 %
2. 2.📏 In the water-pipe picture of a circuit, current is like … (a) the water pressure (b) the pipe colour (c) the flow of water (d) a narrow pipe
3. 3.🔺 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
4. 4.🔺 A current of 20 mA flows through a 330 Ω resistor. What is the voltage across it (in volts)? =
5. 5.🧮 A 16 V battery is joined to 12 Ω and 4 Ω resistors in series. What current flows (in amperes)? =
6. 6.🔺 A 0.5 V supply is joined across a 5 Ω resistor. What current flows (in amperes)? =
7. 7.🧾 A 50 W appliance runs for 4 hours. How many units (kWh) of electricity does it use? =
8. 8.True or false: the ammeter is joined in series. (a) True (b) False
9. 9.🧾 Which lamp gives the same light for the least power? (a) a candle (b) an LED lamp (c) an oil lamp (d) a filament bulb
10. 10.📏 How many ohms make 1 kilo-ohm (kΩ)? (a) 10 (b) 1024 (c) 100 (d) 1000
11. 11.🔺 A current of 0.25 A flows when 1.25 V is joined across a resistor. What is its resistance (in ohms)?
12. 12.💡 A red LED (it uses 2 V) is joined with a 100 Ω resistor to a 3.5 V supply. What current flows (in mA)?
13. 13.🔺 A 10 V supply is joined across a 10 Ω resistor. What current flows (in amperes)? =
14. 14.🔺 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
15. 15.🔺 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
16. 16.💡 Does it save or waste electricity to close the fridge quickly? (a) wastes electricity (b) saves electricity
17. 17.🔺 A current of 50 mA flows through a 120 Ω resistor. What is the voltage across it (in volts)? =
18. 18.🔺 A current of 0.1 A flows when 1.5 V is joined across a resistor. What is its resistance (in ohms)?
19. 19.⚡ Which formula gives electric power? (a) P = V × I (b) P = V ÷ I (c) P = I ÷ V (d) P = V + I
20. 20.Which of these is measured in ohms (Ω)? (a) the flow of charge (b) power (c) how much a part resists (d) energy used each second
21. 21.🔺 A current of 0.2 A flows through a 4 Ω resistor. What is the voltage across it (in volts)? =
22. 22.🔺 A 6 V supply is joined across a 2 Ω resistor. What current flows (in amperes)? =
23. 23.🧩 Which part changes electrical energy into sound? (a) a capacitor (b) a buzzer (c) a diode (d) a resistor
24. 24.What does a potentiometer do? (a) is a resistance knob (b) senses how hot it is (c) makes a beeping sound (d) makes things spin
25. 25.📏 Which unit measures current? (a) watt (W) (b) volt (V) (c) ampere (A) (d) ohm (Ω)
26. 26.💡 On an LED, is the leg by the flat edge the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
27. 27.🔺 A current of 1.5 A flows through a 20 Ω resistor. What is the voltage across it (in volts)? =
28. 28.🧾 A 60 W filament bulb is swapped for a 9 W LED lamp that gives about the same light. Both would run for 2 hours. How many watt-hours (Wh) are saved?
29. 29.⚡ Power tells us … (a) energy used each second (b) the colour of light (c) the size of a cell (d) the length of a wire
30. 30.⚡ A home appliance on the 230 V mains takes 10 A. What is its power (in watts)?
31. 31.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 69000 Ω resistor? (a) blue-white-orange (b) blue-white-red (c) blue-white-yellow (d) white-blue-orange
32. 32.⚡ A 0.5 W device works on 5 V. What current does it take (in amperes)? =
33. 33.💡 A blue LED uses 3 V and should get 25 mA. It runs from a 9 V supply. What resistor (in ohms) is needed in series?
34. 34.Which of these is measured in ohms (Ω)? (a) current (b) energy used each second (c) voltage (d) resistance
35. 35.🌈 In the resistor colour code, which number does orange stand for?
36. 36.🧮 Resistors of 100 Ω and 150 Ω are joined in series. What is the total resistance (in ohms)?
37. 37.🔺 A 15 V supply is joined across a 6 Ω resistor. What current flows (in amperes)? =
38. 38.Which of these is measured in watts (W)? (a) the flow of charge (b) current (c) power (d) the push of a cell
39. 39.📏 How many watts (W) is 4.3 kW?
40. 40.📏 Voltmeter or ammeter: which one is joined in series? (a) ammeter (b) voltmeter

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