Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 148 · 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.🧮 Two equal 40 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
2. 2.🔺 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
3. 3.🧩 Which component lets current go one way? (a) diode (b) buzzer (c) LED (d) transistor
4. 4.🧩 Which part changes electrical energy into movement? (a) a motor (b) a fuse (c) a resistor (d) an LED
5. 5.True or false: a transistor stores a little charge. (a) False (b) True
6. 6.🔍 Which is the odd one out? (a) use daylight to read (b) run fans in empty rooms (c) use LED lamps (d) unplug idle chargers
7. 7.💡 What happens if an LED is put in backwards? (a) it makes a sound (b) it does not light (c) it lights brighter (d) it changes colour
8. 8.🧮 Resistors of 33 Ω, 100 Ω and 330 Ω are joined in series. What is the total resistance (in ohms)?
9. 9.🔺 A 6 V supply is joined across a 300 Ω resistor. What current flows (in milliamperes, mA)?
10. 10.🧾 A 1500 W appliance runs for 4 hours. How many units (kWh) of electricity does it use? =
11. 11.🧮 A 10 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)?
12. 12.🧮 Resistors of 33 Ω and 10 Ω are joined in series. What is the total resistance (in ohms)?
13. 13.💡 On an LED, is the longer leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
14. 14.🧾 A 60 W filament bulb is swapped for a 9 W LED lamp that gives about the same light. Both would run for 10 hours. How many watt-hours (Wh) are saved?
15. 15.🧮 A 1.2 V battery is joined to 3 Ω and 3 Ω resistors in series. What current flows (in amperes)? =
16. 16.True or false: a diode lets current go one way. (a) False (b) True
17. 17.🌈 A resistor has the colour bands violet, green, black. What is its value (in ohms)?
18. 18.🧩 Which component beeps for an alarm? (a) motor (b) buzzer (c) resistor (d) thermistor
19. 19.🧮 Two equal 330 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
20. 20.⚡ Which formula gives electric power? (a) P = V + I (b) P = I ÷ V (c) P = V × I (d) P = V ÷ I
21. 21.True or false: to leave fridge door open saves electricity. (a) False (b) True
22. 22.💡 A red LED (it uses 2 V) is joined with a 150 Ω resistor to a 3.5 V supply. What current flows (in mA)?
23. 23.🔺 A current of 40 mA flows when 18.8 V is joined across a resistor. What is its resistance (in ohms)?
24. 24.⚡ A device works on 9 V and takes 2 A. What is its power (in watts)? =
25. 25.🧮 Adding another resistor in series makes the total resistance … (a) stay the same (b) zero (c) smaller (d) bigger
26. 26.🔺 A 0.6 V supply is joined across a 3 Ω resistor. What current flows (in amperes)? =
27. 27.🔺 A current of 20 mA flows when 2 V is joined across a resistor. What is its resistance (in ohms)?
28. 28.🌈 A resistor has the colour bands yellow, blue, yellow. What is its value in kilo-ohms (kΩ)? =
29. 29.What does a capacitor do? (a) glows using little power (b) blows if current is high (c) smooths a wobbly supply (d) makes things spin
30. 30.True or false: to set the AC to 24 °C wastes electricity. (a) True (b) False
31. 31.🧮 Two resistors in parallel give a total that is … (a) their sum (b) more than either one (c) always zero (d) less than either one
32. 32.🔺 In the V-I-R triangle, how do we find V? (a) V = I + R (b) V = I ÷ R (c) V = R ÷ I (d) V = I × R
33. 33.🧾 A 60 W filament bulb is swapped for a 9 W LED lamp that gives about the same light. Both would run for 7 hours. How many watt-hours (Wh) are saved?
34. 34.🌈 A resistor has the colour bands grey, violet, yellow. What is its value in kilo-ohms (kΩ)? =
35. 35.💡 On an LED, is the shorter leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
36. 36.⚡ Power tells us … (a) energy used each second (b) the colour of light (c) the size of a cell (d) the length of a wire
37. 37.🔺 In the V-I-R triangle, how do we find I? (a) I = V ÷ R (b) I = R ÷ V (c) I = V + R (d) I = V × R
38. 38.🔺 A current of 2 A flows when 40 V is joined across a resistor. What is its resistance (in ohms)?
39. 39.🧮 Resistors of 100 Ω, 150 Ω, 330 Ω and 10 Ω are joined in series. What is the total resistance (in ohms)?
40. 40.💡 A blue LED uses 3 V and should get 25 mA. It runs from a 9 V supply. What resistor (in ohms) is needed in series?

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