Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 646 · 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 220 Ω resistor is joined in series with two equal 220 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
2. 2.⚡ 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
3. 3.📏 Voltmeter or ammeter: which one measures voltage? (a) ammeter (b) voltmeter
4. 4.⚡ A home appliance on the 230 V mains takes 0.5 A. What is its power (in watts)?
5. 5.📏 Which unit measures the push of a cell? (a) volt (V) (b) ampere (A) (c) watt (W) (d) ohm (Ω)
6. 6.🔺 A current of 10 mA flows through a 470 Ω resistor. What is the voltage across it (in volts)? =
7. 7.True or false: on an LED, the longer leg is the cathode (−). (a) True (b) False
8. 8.💡 Does it save or waste electricity to use daylight to read? (a) wastes electricity (b) saves electricity
9. 9.💡 Does it save or waste electricity to leave fridge door open? (a) saves electricity (b) wastes electricity
10. 10.📏 Voltmeter or ammeter: which one measures current? (a) voltmeter (b) ammeter
11. 11.🧮 A 1.4 V battery is joined to 3 Ω and 4 Ω resistors in series. What current flows (in amperes)? =
12. 12.💡 Does it save or waste electricity to close the fridge quickly? (a) saves electricity (b) wastes electricity
13. 13.🌈 A resistor has the colour bands orange, black, black. What is its value (in ohms)?
14. 14.📏 How many kilowatts (kW) is 4450 W? =
15. 15.💡 Does it save or waste electricity to set the AC to 24 °C? (a) wastes electricity (b) saves electricity
16. 16.🔺 A current of 2 A flows through a 3 Ω resistor. What is the voltage across it (in volts)? =
17. 17.What does a resistor do? (a) lets current go one way (b) smooths a wobbly supply (c) limits the current (d) senses how hot it is
18. 18.🔺 A current of 10 mA flows when 1.2 V is joined across a resistor. What is its resistance (in ohms)?
19. 19.⚡ An 18 W device works on 6 V. What current does it take (in amperes)? =
20. 20.🧮 Resistors of 220 Ω, 47 Ω, 10 Ω and 100 Ω are joined in series. What is the total resistance (in ohms)?
21. 21.🔺 A current of 0.2 A flows through a 2 Ω resistor. What is the voltage across it (in volts)? =
22. 22.🌈 A gold fourth band on a resistor means the value may be off by … (a) 25 % (b) 0 % (c) 5 % (d) 50 %
23. 23.🌈 Which band is read first on a resistor? (a) any band (b) the widest gap (c) the gold band (d) the one nearest an end
24. 24.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 99 Ω resistor? (a) white-white-brown (b) white-white-black (c) white-black-black (d) brown-white-black
25. 25.🧮 Two equal 220 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
26. 26.🌈 A resistor has the colour bands violet, blue, red. What is its value (in ohms)?
27. 27.🧮 A 1.8 V battery is joined to 12 Ω and 6 Ω resistors in series. What current flows (in amperes)? =
28. 28.🔺 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
29. 29.🧾 A 75 W filament bulb is swapped for a 12 W LED lamp that gives about the same light. Both would run for 5 hours. How many watt-hours (Wh) are saved?
30. 30.🔺 A current of 0.5 A flows through an 8 Ω resistor. What is the voltage across it (in volts)? =
31. 31.📏 How many milliamperes (mA) is 2.99 A?
32. 32.🌈 A resistor has the colour bands orange, red, orange. What is its value in kilo-ohms (kΩ)? =
33. 33.🧩 Which component has coloured bands? (a) LED (b) fuse (c) LDR (d) resistor
34. 34.🔺 A current of 40 mA flows when 4.8 V is joined across a resistor. What is its resistance (in ohms)?
35. 35.True or false: on an LED, the shorter leg is the cathode (−). (a) False (b) True
36. 36.🔺 An 8 V supply is joined across an 8 Ω resistor. What current flows (in amperes)? =
37. 37.🔺 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
38. 38.💡 Why does an LED need a resistor in series? (a) to make it brighter (b) to change its colour (c) to limit the current (d) to store charge
39. 39.🌈 A resistor has the colour bands white, orange, red. What is its value in kilo-ohms (kΩ)? =
40. 40.⚡ Which formula gives electric power? (a) P = V ÷ I (b) P = V + I (c) P = I ÷ V (d) P = V × I

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