Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 313 · 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) 0 % (b) 50 % (c) 25 % (d) 5 %
2. 2.🔺 A current of 0.5 A flows through a 12 Ω resistor. What is the voltage across it (in volts)? =
3. 3.⚡ A home appliance on the 230 V mains takes 2 A. What is its power (in watts)?
4. 4.🧮 Two equal 100 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
5. 5.🌈 In the resistor colour code, which number does red stand for?
6. 6.🔺 A current of 20 mA flows through a 400 Ω resistor. What is the voltage across it (in volts)? =
7. 7.True or false: the flow of charge is measured in amperes (A). (a) False (b) True
8. 8.⚡ A device works on 3 V and takes 0.1 A. What is its power (in watts)? =
9. 9.Which of these is measured in ohms (Ω)? (a) energy used each second (b) the push of a cell (c) current (d) how much a part resists
10. 10.🌈 In the resistor colour code, which number does yellow stand for?
11. 11.🧮 A 7 V battery is joined to 2 Ω and 12 Ω resistors in series. What current flows (in amperes)? =
12. 12.🧩 Which component stores a little charge? (a) LDR (b) buzzer (c) capacitor (d) diode
13. 13.True or false: a transistor makes a beeping sound. (a) True (b) False
14. 14.🔺 A current of 25 mA flows when 8.25 V is joined across a resistor. What is its resistance (in ohms)?
15. 15.⚡ A device works on 3 V and takes 2 A. What is its power (in watts)? =
16. 16.💡 On an LED, is the longer leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
17. 17.🔺 A 4.4 V supply is joined across a 220 Ω resistor. What current flows (in milliamperes, mA)?
18. 18.🧮 A 150 Ω resistor is joined in series with two equal 20 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
19. 19.💡 On an LED, is the shorter leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
20. 20.📏 Which unit measures power? (a) volt (V) (b) watt (W) (c) ampere (A) (d) ohm (Ω)
21. 21.💡 On an LED, is the round-side leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
22. 22.🧩 A capacitor in a circuit can … (a) make light (b) spin a wheel (c) measure heat (d) store charge briefly
23. 23.🔺 A 9 V supply is joined across a 6 Ω resistor. What current flows (in amperes)? =
24. 24.🧮 Resistors of 22 Ω, 10 Ω, 10 Ω and 20 Ω are joined in series. What is the total resistance (in ohms)?
25. 25.⚡ A 3 W device works on 6 V. What current does it take (in amperes)? =
26. 26.💡 Does it save or waste electricity to close the fridge quickly? (a) wastes electricity (b) saves electricity
27. 27.🔺 A 1.2 V supply is joined across a 120 Ω resistor. What current flows (in milliamperes, mA)?
28. 28.🌈 A resistor has the colour bands yellow, white, yellow. What is its value in kilo-ohms (kΩ)? =
29. 29.Which of these wastes electricity? (a) run fans in empty rooms (b) set the AC to 24 °C (c) use LED lamps (d) switch off empty rooms
30. 30.🔺 In the V-I-R triangle, how do we find V? (a) V = R ÷ I (b) V = I + R (c) V = I × R (d) V = I ÷ R
31. 31.💡 Why does an LED need a resistor in series? (a) to make it brighter (b) to change its colour (c) to store charge (d) to limit the current
32. 32.📏 Voltmeter or ammeter: which one measures current? (a) voltmeter (b) ammeter
33. 33.🌈 Which band is read first on a resistor? (a) the widest gap (b) any band (c) the one nearest an end (d) the gold band
34. 34.💡 A red LED (it uses 2 V) is joined with a 300 Ω resistor to a 3.5 V supply. What current flows (in mA)?
35. 35.📏 How many milliamperes (mA) is 1.16 A?
36. 36.📏 Voltmeter or ammeter: which one measures voltage? (a) voltmeter (b) ammeter
37. 37.🌈 In the resistor colour code, which number does black stand for?
38. 38.🔺 A current of 0.1 A flows through a 15 Ω resistor. What is the voltage across it (in volts)? =
39. 39.🧮 A 0.5 V battery is joined to 2 Ω and 3 Ω resistors in series. What current flows (in amperes)? =
40. 40.💡 Does it save or waste electricity to iron one shirt at a time? (a) wastes electricity (b) saves electricity

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