Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 83 · 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 leg by the flat edge the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
2. 2.🔺 A current of 1.5 A flows through an 8 Ω resistor. What is the voltage across it (in volts)? =
3. 3.🔺 A 7.5 V supply is joined across a 150 Ω resistor. What current flows (in milliamperes, mA)?
4. 4.⚡ Power tells us … (a) the size of a cell (b) energy used each second (c) the length of a wire (d) the colour of light
5. 5.📏 Which unit measures energy used each second? (a) ohm (Ω) (b) watt (W) (c) volt (V) (d) ampere (A)
6. 6.True or false: the voltmeter measures current. (a) False (b) True
7. 7.🔺 A current of 10 mA flows through a 150 Ω resistor. What is the voltage across it (in volts)? =
8. 8.🧾 One “unit” on an electricity bill is … (a) 1 kilowatt-hour (kWh) (b) 1 volt (c) 1 watt (d) 1 ampere
9. 9.⚡ A 27 W device works on 9 V. What current does it take (in amperes)? =
10. 10.🔺 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
11. 11.🔺 A current of 10 mA flows when 2.5 V is joined across a resistor. What is its resistance (in ohms)?
12. 12.🔺 A 6 V supply is joined across a 300 Ω resistor. What current flows (in milliamperes, mA)?
13. 13.True or false: to set the AC to 24 °C wastes electricity. (a) True (b) False
14. 14.🧩 Which component has coloured bands? (a) capacitor (b) diode (c) resistor (d) motor
15. 15.🌈 In the resistor colour code, which number does blue stand for?
16. 16.🧮 Resistors of 47 Ω, 10 Ω, 100 Ω and 47 Ω are joined in series. What is the total resistance (in ohms)?
17. 17.True or false: a thermistor smooths a wobbly supply. (a) True (b) False
18. 18.🔺 A current of 0.1 A flows through a 4 Ω resistor. What is the voltage across it (in volts)? =
19. 19.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) becomes zero (b) gets bigger (c) gets smaller (d) stays the same
20. 20.💡 Why does an LED need a resistor in series? (a) to limit the current (b) to change its colour (c) to make it brighter (d) to store charge
21. 21.True or false: to use old filament bulbs saves electricity. (a) True (b) False
22. 22.What does a resistor do? (a) stores a little charge (b) is a resistance knob (c) has coloured bands (d) makes a beeping sound
23. 23.Which of these is measured in amperes (A)? (a) the flow of charge (b) the push of a cell (c) power (d) energy used each second
24. 24.🔺 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
25. 25.📏 Voltmeter or ammeter: which one is joined across a part? (a) voltmeter (b) ammeter
26. 26.True or false: to unplug idle chargers saves electricity. (a) True (b) False
27. 27.💡 Does it save or waste electricity to run fans in empty rooms? (a) saves electricity (b) wastes electricity
28. 28.🔺 A current of 0.2 A flows through a 5 Ω resistor. What is the voltage across it (in volts)? =
29. 29.🔺 A current of 0.5 A flows through a 5 Ω resistor. What is the voltage across it (in volts)? =
30. 30.What does a thermistor do? (a) makes things spin (b) has coloured bands (c) senses how hot it is (d) lets current go one way
31. 31.True or false: energy used each second is measured in ohms (Ω). (a) True (b) False
32. 32.🧮 Five equal 100 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
33. 33.💡 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) may burn out (b) does not light (c) lights up
34. 34.📏 How many kilo-ohms (kΩ) is 9100 Ω? =
35. 35.🌈 Which band is read first on a resistor? (a) the gold band (b) the one nearest an end (c) the widest gap (d) any band
36. 36.🔺 A 10 V supply is joined across a 400 Ω resistor. What current flows (in milliamperes, mA)?
37. 37.📏 Which unit measures how much a part resists? (a) volt (V) (b) ampere (A) (c) ohm (Ω) (d) watt (W)
38. 38.🧮 Three equal 150 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
39. 39.True or false: the ammeter is joined across a part. (a) False (b) True
40. 40.🧮 A 3 V battery is joined to 12 Ω and 3 Ω resistors in series. What current flows (in amperes)? =

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