Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 178 · 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.💡 On an LED, is the round-side leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
2. 2.🧮 Two equal 330 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
3. 3.🌈 Which band is read first on a resistor? (a) the one nearest an end (b) the widest gap (c) the gold band (d) any band
4. 4.🔺 A current of 25 mA flows when 8.25 V is joined across a resistor. What is its resistance (in ohms)?
5. 5.🧩 Which component smooths a wobbly supply? (a) motor (b) resistor (c) capacitor (d) potentiometer
6. 6.🧮 Three equal 75 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
7. 7.💡 Does it save or waste electricity to use LED lamps? (a) saves electricity (b) wastes electricity
8. 8.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 94 Ω resistor? (a) yellow-white-black (b) brown-yellow-black (c) white-yellow-brown (d) white-yellow-black
9. 9.📏 How many milliamperes (mA) is 0.15 A?
10. 10.🔺 A current of 0.1 A flows through a 2 Ω resistor. What is the voltage across it (in volts)? =
11. 11.Which of these is measured in ohms (Ω)? (a) power (b) voltage (c) the push of a cell (d) resistance
12. 12.🧾 One “unit” on an electricity bill is … (a) 1 kilowatt-hour (kWh) (b) 1 volt (c) 1 ampere (d) 1 watt
13. 13.🧮 Three equal 60 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
14. 14.What does a potentiometer do? (a) smooths a wobbly supply (b) senses how bright it is (c) blows if current is high (d) is a resistance knob
15. 15.🌈 In the resistor colour code, which number does brown stand for?
16. 16.🌈 A resistor has the colour bands yellow, green, red. What is its value (in ohms)?
17. 17.🧮 A 3 V battery is joined to 3 Ω and 3 Ω resistors in series. What current flows (in amperes)? =
18. 18.💡 An LED is joined to a 6 V battery through a 1000 Ω resistor; the leg next to the flat edge of its rim goes to the + side. What happens? (a) lights up (b) may burn out (c) does not light
19. 19.💡 A red LED uses 2 V and should get 10 mA. It runs from a 12 V supply. What resistor (in ohms) is needed in series?
20. 20.🔺 A current of 0.5 A flows through a 20 Ω resistor. What is the voltage across it (in volts)? =
21. 21.🧮 A 0.4 V battery is joined to 2 Ω and 2 Ω resistors in series. What current flows (in amperes)? =
22. 22.📏 In the water-pipe picture of a circuit, voltage is like … (a) the water pressure (b) the pipe colour (c) the water tank lid (d) the tap handle
23. 23.🔺 A current of 20 mA flows when 10 V is joined across a resistor. What is its resistance (in ohms)?
24. 24.🔺 A current of 1 A flows through a 4 Ω resistor. What is the voltage across it (in volts)? =
25. 25.💡 Does it save or waste electricity to leave fridge door open? (a) saves electricity (b) wastes electricity
26. 26.⚡ Power tells us … (a) the colour of light (b) the size of a cell (c) the length of a wire (d) energy used each second
27. 27.🔺 A current of 20 mA flows when 6.6 V is joined across a resistor. What is its resistance (in ohms)?
28. 28.🔺 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
29. 29.📏 Voltmeter or ammeter: which one measures voltage? (a) ammeter (b) voltmeter
30. 30.True or false: voltage is measured in ohms (Ω). (a) True (b) False
31. 31.🧮 Resistors of 150 Ω, 47 Ω and 47 Ω are joined in series. What is the total resistance (in ohms)?
32. 32.🔺 A current of 2.5 A flows through a 6 Ω resistor. What is the voltage across it (in volts)? =
33. 33.🌈 In the resistor colour code, which number does orange stand for?
34. 34.💡 Why does an LED need a resistor in series? (a) to change its colour (b) to limit the current (c) to make it brighter (d) to store charge
35. 35.🧮 A 22 Ω resistor is joined in series with two equal 200 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
36. 36.True or false: to run fans in empty rooms saves electricity. (a) False (b) True
37. 37.🔺 A current of 10 mA flows through a 300 Ω resistor. What is the voltage across it (in volts)? =
38. 38.🧮 Resistors of 33 Ω and 150 Ω are joined in series. What is the total resistance (in ohms)?
39. 39.True or false: the voltmeter measures current. (a) True (b) False
40. 40.🔺 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

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