Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 979 · 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 home appliance on the 230 V mains takes 8 A. What is its power (in watts)?
2. 2.⚡ Which formula gives electric power? (a) P = V ÷ I (b) P = I ÷ V (c) P = V × I (d) P = V + I
3. 3.🔺 A current of 0.2 A flows through a 20 Ω resistor. What is the voltage across it (in volts)? =
4. 4.🔺 In the V-I-R triangle, how do we find R? (a) R = V × I (b) R = V ÷ I (c) R = I ÷ V (d) R = V + I
5. 5.🔺 A current of 0.2 A flows through a 3 Ω resistor. What is the voltage across it (in volts)? =
6. 6.True or false: on an LED, the shorter leg is the anode (+). (a) False (b) True
7. 7.📏 Voltmeter or ammeter: which one is joined across a part? (a) ammeter (b) voltmeter
8. 8.🌈 A resistor has the colour bands white, violet, orange. What is its value (in ohms)?
9. 9.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) stays the same (b) becomes zero (c) gets bigger (d) gets smaller
10. 10.🔺 A current of 0.5 A flows through a 6 Ω resistor. What is the voltage across it (in volts)? =
11. 11.⚡ A home appliance on the 230 V mains takes 10 A. What is its power (in watts)?
12. 12.💡 A red LED uses 2 V and should get 20 mA. It runs from a 6 V supply. What resistor (in ohms) is needed in series?
13. 13.🧩 A capacitor in a circuit can … (a) store charge briefly (b) make light (c) measure heat (d) spin a wheel
14. 14.📏 How many ohms make 1 kilo-ohm (kΩ)? (a) 10 (b) 1024 (c) 100 (d) 1000
15. 15.💡 A red LED (it uses 2 V) is joined with a 100 Ω resistor to a 3 V supply. What current flows (in mA)?
16. 16.🔺 A current of 20 mA flows through a 200 Ω resistor. What is the voltage across it (in volts)? =
17. 17.📏 How many kilo-ohms (kΩ) is 8400 Ω? =
18. 18.True or false: the ammeter measures current. (a) False (b) True
19. 19.📏 Which unit measures the push of a cell? (a) watt (W) (b) ampere (A) (c) ohm (Ω) (d) volt (V)
20. 20.🧮 A 3.5 V battery is joined to 4 Ω and 3 Ω resistors in series. What current flows (in amperes)? =
21. 21.💡 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)?
22. 22.🔺 A 10 V supply is joined across a 250 Ω resistor. What current flows (in milliamperes, mA)?
23. 23.🧮 Resistors of 20 Ω and 150 Ω are joined in series. What is the total resistance (in ohms)?
24. 24.🧾 Which lamp gives the same light for the least power? (a) an oil lamp (b) a candle (c) a filament bulb (d) an LED lamp
25. 25.🌈 A gold fourth band on a resistor means the value may be off by … (a) 0 % (b) 5 % (c) 50 % (d) 25 %
26. 26.True or false: an LED makes a beeping sound. (a) False (b) True
27. 27.💡 A red LED (it uses 2 V) is joined with a 300 Ω resistor to a 5 V supply. What current flows (in mA)?
28. 28.What does a diode do? (a) lets current go one way (b) stores a little charge (c) makes a beeping sound (d) is a resistance knob
29. 29.📏 In the water-pipe picture of a circuit, current is like … (a) a narrow pipe (b) the pipe colour (c) the flow of water (d) the water pressure
30. 30.Which of these is measured in ohms (Ω)? (a) current (b) resistance (c) the push of a cell (d) power
31. 31.🔺 A 16 V supply is joined across a 400 Ω resistor. What current flows (in milliamperes, mA)?
32. 32.Which of these saves electricity? (a) iron one shirt at a time (b) run fans in empty rooms (c) use LED lamps (d) use old filament bulbs
33. 33.What does a potentiometer do? (a) blows if current is high (b) senses how bright it is (c) is a resistance knob (d) beeps for an alarm
34. 34.🧮 Five equal 125 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
35. 35.What does a buzzer do? (a) glows using little power (b) beeps for an alarm (c) has coloured bands (d) stores a little charge
36. 36.🔺 A current of 1 A flows when 12 V is joined across a resistor. What is its resistance (in ohms)?
37. 37.🧮 Resistors of 47 Ω, 470 Ω and 330 Ω are joined in series. What is the total resistance (in ohms)?
38. 38.💡 On an LED, is the longer leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
39. 39.🔺 A current of 0.25 A flows when 1 V is joined across a resistor. What is its resistance (in ohms)?
40. 40.🧮 A 4 V battery is joined to 12 Ω and 4 Ω resistors in series. What current flows (in amperes)? =

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