Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 869 · 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.🔺 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
2. 2.🔺 A current of 10 mA flows through a 330 Ω resistor. What is the voltage across it (in volts)? =
3. 3.🌈 In the resistor colour code, which number does black stand for?
4. 4.What does a fuse do? (a) makes things spin (b) is a resistance knob (c) stores a little charge (d) blows if current is high
5. 5.⚡ A 2.25 W device works on 9 V. What current does it take (in amperes)? =
6. 6.🔺 A current of 2 A flows through a 2 Ω resistor. What is the voltage across it (in volts)? =
7. 7.⚡ A 5 W device works on 5 V. What current does it take (in amperes)? =
8. 8.🌈 A resistor has the colour bands red, red, black. What is its value (in ohms)?
9. 9.⚡ A 6 W device works on 6 V. What current does it take (in amperes)? =
10. 10.True or false: the push of a cell is measured in ohms (Ω). (a) True (b) False
11. 11.📏 Which unit measures the flow of charge? (a) volt (V) (b) watt (W) (c) ampere (A) (d) ohm (Ω)
12. 12.🧮 Two resistors in parallel give a total that is … (a) less than either one (b) their sum (c) always zero (d) more than either one
13. 13.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) gets bigger (b) becomes zero (c) stays the same (d) gets smaller
14. 14.🧾 A 75 W filament bulb is swapped for a 12 W LED lamp that gives about the same light. Both would run for 6 hours. How many watt-hours (Wh) are saved?
15. 15.🔺 A current of 10 mA flows through a 200 Ω resistor. What is the voltage across it (in volts)? =
16. 16.💡 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)?
17. 17.💡 A red LED (it uses 2 V) is joined with a 200 Ω resistor to a 5 V supply. What current flows (in mA)?
18. 18.🧩 A capacitor in a circuit can … (a) measure heat (b) make light (c) store charge briefly (d) spin a wheel
19. 19.🔺 A current of 0.1 A flows when 0.4 V is joined across a resistor. What is its resistance (in ohms)?
20. 20.🌈 A resistor has the colour bands violet, yellow, red. What is its value in kilo-ohms (kΩ)? =
21. 21.⚡ A home appliance on the 230 V mains takes 0.5 A. What is its power (in watts)?
22. 22.🧮 A 5.5 V battery is joined to 3 Ω and 8 Ω resistors in series. What current flows (in amperes)? =
23. 23.True or false: to use old filament bulbs wastes electricity. (a) False (b) True
24. 24.What does a buzzer do? (a) limits the current (b) makes a beeping sound (c) stores a little charge (d) makes things spin
25. 25.🧮 Adding another resistor in series makes the total resistance … (a) stay the same (b) smaller (c) zero (d) bigger
26. 26.📏 How many amperes (A) is 110 mA? =
27. 27.True or false: the flow of charge is measured in ohms (Ω). (a) True (b) False
28. 28.🌈 Which band is read first on a resistor? (a) the gold band (b) the widest gap (c) any band (d) the one nearest an end
29. 29.True or false: a resistor lets current go one way. (a) False (b) True
30. 30.🔺 A 2.5 V supply is joined across a 10 Ω resistor. What current flows (in amperes)? =
31. 31.🧮 Five equal 50 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
32. 32.🔺 A current of 0.2 A flows when 0.4 V is joined across a resistor. What is its resistance (in ohms)?
33. 33.🧾 Which lamp gives the same light for the least power? (a) a candle (b) an oil lamp (c) a filament bulb (d) an LED lamp
34. 34.🔺 A current of 50 mA flows through a 120 Ω resistor. What is the voltage across it (in volts)? =
35. 35.🧩 Which component senses how hot it is? (a) buzzer (b) fuse (c) thermistor (d) motor
36. 36.💡 On an LED, is the leg by the flat edge the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
37. 37.💡 Does it save or waste electricity to iron one shirt at a time? (a) saves electricity (b) wastes electricity
38. 38.📏 Voltmeter or ammeter: which one is joined in series? (a) ammeter (b) voltmeter
39. 39.🧩 Which component has coloured bands? (a) LDR (b) resistor (c) motor (d) buzzer
40. 40.🔺 A current of 50 mA flows when 23.5 V is joined across a resistor. What is its resistance (in ohms)?

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