Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 984 · 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 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)?
2. 2.⚡ Which formula gives electric power? (a) P = V × I (b) P = V ÷ I (c) P = V + I (d) P = I ÷ V
3. 3.💡 A red LED (it uses 2 V) is joined with a 200 Ω resistor to a 5 V supply. What current flows (in mA)?
4. 4.🧾 A family uses 20 units of electricity in a month and each unit costs ₹4. What is the bill (in ₹)?
5. 5.💡 Why does an LED need a resistor in series? (a) to limit the current (b) to change its colour (c) to store charge (d) to make it brighter
6. 6.💡 On an LED, is the leg by the flat edge the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
7. 7.🌈 A resistor has the colour bands yellow, brown, yellow. What is its value in kilo-ohms (kΩ)? =
8. 8.⚡ A device works on 6 V and takes 0.25 A. What is its power (in watts)? =
9. 9.🔺 A current of 50 mA flows through a 500 Ω resistor. What is the voltage across it (in volts)? =
10. 10.🧮 Four equal 400 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
11. 11.🧮 Four equal 40 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
12. 12.🔺 In the V-I-R triangle, how do we find V? (a) V = I ÷ R (b) V = R ÷ I (c) V = I × R (d) V = I + R
13. 13.🔺 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
14. 14.💡 What happens if an LED is put in backwards? (a) it changes colour (b) it lights brighter (c) it makes a sound (d) it does not light
15. 15.What does a fuse do? (a) lets current go one way (b) has coloured bands (c) is a resistance knob (d) blows if current is high
16. 16.🔺 A current of 3 A flows through a 6 Ω resistor. What is the voltage across it (in volts)? =
17. 17.🔺 A 22.5 V supply is joined across a 15 Ω resistor. What current flows (in amperes)? =
18. 18.🧩 Which component boosts a small signal? (a) transistor (b) capacitor (c) thermistor (d) LDR
19. 19.🧩 Which component blows if current is high? (a) capacitor (b) LED (c) resistor (d) fuse
20. 20.📏 Voltmeter or ammeter: which one is joined across a part? (a) voltmeter (b) ammeter
21. 21.📏 In the water-pipe picture of a circuit, current is like … (a) the pipe colour (b) the water pressure (c) the flow of water (d) a narrow pipe
22. 22.🔺 In the V-I-R triangle, how do we find R? (a) R = V × I (b) R = I ÷ V (c) R = V ÷ I (d) R = V + I
23. 23.📏 Which unit measures the flow of charge? (a) ampere (A) (b) ohm (Ω) (c) volt (V) (d) watt (W)
24. 24.🧮 Two equal 330 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
25. 25.🔺 A current of 10 mA flows when 4 V is joined across a resistor. What is its resistance (in ohms)?
26. 26.🧩 Which component lets current go one way? (a) fuse (b) buzzer (c) diode (d) LED
27. 27.📏 Voltmeter or ammeter: which one measures voltage? (a) voltmeter (b) ammeter
28. 28.📏 How many kilowatts (kW) is 3700 W? =
29. 29.⚡ A 72 W device works on 24 V. What current does it take (in amperes)? =
30. 30.⚡ A device works on 12 V and takes 1 A. What is its power (in watts)? =
31. 31.🔺 A current of 25 mA flows through a 470 Ω resistor. What is the voltage across it (in volts)? =
32. 32.🧮 Two equal 220 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
33. 33.⚡ A 1.25 W device works on 5 V. What current does it take (in amperes)? =
34. 34.🧩 Which part changes electrical energy into sound? (a) a diode (b) a buzzer (c) a capacitor (d) a resistor
35. 35.🧩 Which component turns a fan or wheels? (a) LED (b) buzzer (c) motor (d) LDR
36. 36.🔺 A current of 0.5 A flows when 2.5 V is joined across a resistor. What is its resistance (in ohms)?
37. 37.🔺 A current of 25 mA flows through a 120 Ω resistor. What is the voltage across it (in volts)? =
38. 38.🔺 A current of 1.5 A flows through a 6 Ω resistor. What is the voltage across it (in volts)? =
39. 39.📏 How many kilo-ohms (kΩ) is 7700 Ω? =
40. 40.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark an 8100 Ω resistor? (a) grey-brown-brown (b) brown-grey-red (c) grey-brown-orange (d) grey-brown-red

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