Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 934 · 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 current of 20 mA flows when 5 V is joined across a resistor. What is its resistance (in ohms)?
2. 2.💡 A red LED (it uses 2 V) is joined with a 300 Ω resistor to a 5 V supply. What current flows (in mA)?
3. 3.📏 How many watts (W) is 5 kW?
4. 4.What does an LED do? (a) is a resistance knob (b) smooths a wobbly supply (c) stores a little charge (d) glows using little power
5. 5.True or false: to use daylight to read wastes electricity. (a) False (b) True
6. 6.📏 Which unit measures resistance? (a) ampere (A) (b) volt (V) (c) watt (W) (d) ohm (Ω)
7. 7.⚡ Which formula gives electric power? (a) P = V × I (b) P = V ÷ I (c) P = I ÷ V (d) P = V + I
8. 8.🔺 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
9. 9.🌈 Which band is read first on a resistor? (a) the widest gap (b) the one nearest an end (c) any band (d) the gold band
10. 10.⚡ A device works on 5 V and takes 0.2 A. What is its power (in watts)? =
11. 11.True or false: a buzzer makes a beeping sound. (a) False (b) True
12. 12.🧮 Resistors of 33 Ω, 33 Ω and 33 Ω are joined in series. What is the total resistance (in ohms)?
13. 13.📏 How many kilo-ohms (kΩ) is 9500 Ω? =
14. 14.🧮 A 150 Ω resistor is joined in series with two equal 10 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
15. 15.True or false: the voltmeter measures current. (a) False (b) True
16. 16.🌈 A resistor has the colour bands grey, green, orange. What is its value in kilo-ohms (kΩ)? =
17. 17.🧩 Which component boosts a small signal? (a) buzzer (b) transistor (c) capacitor (d) motor
18. 18.True or false: a potentiometer beeps for an alarm. (a) True (b) False
19. 19.💡 On an LED, is the shorter leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
20. 20.True or false: a transistor smooths a wobbly supply. (a) True (b) False
21. 21.🧾 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
22. 22.⚡ A device works on 3 V and takes 3 A. What is its power (in watts)? =
23. 23.🧮 A 10 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)?
24. 24.💡 Does it save or waste electricity to use LED lamps? (a) wastes electricity (b) saves electricity
25. 25.🔺 In the V-I-R triangle, how do we find I? (a) I = V + R (b) I = V × R (c) I = V ÷ R (d) I = R ÷ V
26. 26.🔺 A current of 3 A flows through a 15 Ω resistor. What is the voltage across it (in volts)? =
27. 27.🧮 Five equal 100 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
28. 28.📏 How many kilo-ohms (kΩ) is 7900 Ω? =
29. 29.True or false: the voltmeter measures voltage. (a) True (b) False
30. 30.🌈 A resistor has the colour bands grey, black, orange. What is its value in kilo-ohms (kΩ)? =
31. 31.🔺 A current of 25 mA flows through a 100 Ω resistor. What is the voltage across it (in volts)? =
32. 32.🔺 A current of 1.5 A flows through a 3 Ω resistor. What is the voltage across it (in volts)? =
33. 33.True or false: the flow of charge is measured in watts (W). (a) False (b) True
34. 34.📏 How many amperes (A) is 2140 mA? =
35. 35.True or false: on an LED, the longer leg is the cathode (−). (a) False (b) True
36. 36.⚡ Power tells us … (a) the colour of light (b) energy used each second (c) the size of a cell (d) the length of a wire
37. 37.💡 What does LED stand for? (a) large electric dial (b) light energy dial (c) light-emitting diode (d) low energy device
38. 38.🔺 A current of 2.5 A flows through a 6 Ω resistor. What is the voltage across it (in volts)? =
39. 39.💡 Does it save or waste electricity to leave fridge door open? (a) saves electricity (b) wastes electricity
40. 40.🔺 A current of 1 A flows when 15 V is joined across a resistor. What is its resistance (in ohms)?

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