Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 974 · 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 red LED (it uses 2 V) is joined with a 300 Ω resistor to a 5 V supply. What current flows (in mA)?
2. 2.🔺 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
3. 3.📏 How many kilo-ohms (kΩ) is 2300 Ω? =
4. 4.📏 How many watts (W) is 4.6 kW?
5. 5.Which of these saves electricity? (a) use old filament bulbs (b) iron one shirt at a time (c) set the AC to 24 °C (d) run fans in empty rooms
6. 6.⚡ Which formula gives electric power? (a) P = V + I (b) P = V × I (c) P = V ÷ I (d) P = I ÷ V
7. 7.What does a thermistor do? (a) blows if current is high (b) limits the current (c) turns a fan or wheels (d) senses how hot it is
8. 8.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) gets bigger (b) stays the same (c) gets smaller (d) becomes zero
9. 9.💡 A red LED (it uses 2 V) is joined with a 200 Ω resistor to a 4 V supply. What current flows (in mA)?
10. 10.🔺 A current of 0.25 A flows through an 8 Ω resistor. What is the voltage across it (in volts)? =
11. 11.💡 What does LED stand for? (a) low energy device (b) light energy dial (c) light-emitting diode (d) large electric dial
12. 12.True or false: current is measured in amperes (A). (a) False (b) True
13. 13.🔺 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
14. 14.🧩 Which part changes electrical energy into sound? (a) a resistor (b) a buzzer (c) a diode (d) a capacitor
15. 15.🧮 Two equal 1000 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
16. 16.📏 How many amperes (A) is 2760 mA? =
17. 17.True or false: the voltmeter is joined across a part. (a) True (b) False
18. 18.🔺 A 0.4 V supply is joined across a 2 Ω resistor. What current flows (in amperes)? =
19. 19.🧮 A 4.25 V battery is joined to 12 Ω and 5 Ω resistors in series. What current flows (in amperes)? =
20. 20.🔺 A current of 10 mA flows through a 250 Ω resistor. What is the voltage across it (in volts)? =
21. 21.💡 Does it save or waste electricity to unplug idle chargers? (a) wastes electricity (b) saves electricity
22. 22.💡 On an LED, is the round-side leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
23. 23.🌈 A resistor has the colour bands green, brown, yellow. What is its value in kilo-ohms (kΩ)? =
24. 24.🧾 A family uses 120 units of electricity in a month and each unit costs ₹6. What is the bill (in ₹)?
25. 25.🌈 A resistor has the colour bands red, grey, yellow. What is its value in kilo-ohms (kΩ)? =
26. 26.🧮 Resistors of 50 Ω and 50 Ω are joined in series. What is the total resistance (in ohms)?
27. 27.🧾 Which lamp gives the same light for the least power? (a) an LED lamp (b) an oil lamp (c) a candle (d) a filament bulb
28. 28.🔺 In the V-I-R triangle, how do we find I? (a) I = R ÷ V (b) I = V + R (c) I = V × R (d) I = V ÷ R
29. 29.True or false: on an LED, the shorter leg is the anode (+). (a) False (b) True
30. 30.Which of these wastes electricity? (a) switch off empty rooms (b) run fans in empty rooms (c) use LED lamps (d) set the AC to 24 °C
31. 31.🧮 A 150 Ω resistor is joined in series with two equal 470 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
32. 32.💡 On an LED, is the longer leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
33. 33.🧩 Which component glows using little power? (a) fuse (b) diode (c) LED (d) LDR
34. 34.🔺 A 6 V supply is joined across a 2 Ω resistor. What current flows (in amperes)? =
35. 35.💡 On an LED, is the shorter leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
36. 36.🌈 Which band is read first on a resistor? (a) any band (b) the widest gap (c) the gold band (d) the one nearest an end
37. 37.🧮 A 4 V battery is joined to 12 Ω and 4 Ω resistors in series. What current flows (in amperes)? =
38. 38.🔺 A 10 V supply is joined across a 5 Ω resistor. What current flows (in amperes)? =
39. 39.🧾 A 200 W appliance runs for 2 hours. How many units (kWh) of electricity does it use? =
40. 40.🔺 A current of 0.5 A flows through a 12 Ω resistor. What is the voltage across it (in volts)? =

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