Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 218 · 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 family uses 70 units of electricity in a month and each unit costs ₹4. What is the bill (in ₹)?
2. 2.True or false: to iron one shirt at a time saves electricity. (a) False (b) True
3. 3.⚡ A device works on 1.5 V and takes 0.25 A. What is its power (in watts)? =
4. 4.🔺 A current of 20 mA flows when 10 V is joined across a resistor. What is its resistance (in ohms)?
5. 5.💡 On an LED, is the longer leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
6. 6.🔺 A current of 0.1 A flows when 1.2 V is joined across a resistor. What is its resistance (in ohms)?
7. 7.🧩 Which component stores a little charge? (a) resistor (b) fuse (c) potentiometer (d) capacitor
8. 8.🧮 A 3.5 V battery is joined to 3 Ω and 4 Ω resistors in series. What current flows (in amperes)? =
9. 9.🔺 A 6 V supply is joined across a 4 Ω resistor. What current flows (in amperes)? =
10. 10.🧮 Two equal 40 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
11. 11.🌈 A resistor has the colour bands blue, blue, red. What is its value (in ohms)?
12. 12.🧩 A capacitor in a circuit can … (a) spin a wheel (b) measure heat (c) make light (d) store charge briefly
13. 13.🔺 A 4 V supply is joined across a 2 Ω resistor. What current flows (in amperes)? =
14. 14.⚡ A device works on 3 V and takes 0.1 A. What is its power (in watts)? =
15. 15.⚡ Which formula gives electric power? (a) P = V × I (b) P = V ÷ I (c) P = V + I (d) P = I ÷ V
16. 16.🌈 A resistor has the colour bands blue, orange, red. What is its value in kilo-ohms (kΩ)? =
17. 17.🌈 In the resistor colour code, which number does orange stand for?
18. 18.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 97000 Ω resistor? (a) violet-white-orange (b) white-violet-orange (c) white-violet-red (d) white-violet-yellow
19. 19.💡 An LED is joined to a 3 V battery through a 330 Ω resistor; its long leg goes to the + side and its short leg to the − side. What happens? (a) lights up (b) does not light (c) may burn out
20. 20.🧩 Which part changes electrical energy into movement? (a) an LED (b) a motor (c) a fuse (d) a resistor
21. 21.💡 An LED is joined to a 6 V battery with no resistor; its long leg goes to the + side and its short leg to the − side. What happens? (a) does not light (b) may burn out (c) lights up
22. 22.🧩 Which component senses how hot it is? (a) capacitor (b) thermistor (c) resistor (d) motor
23. 23.📏 Voltmeter or ammeter: which one measures current? (a) ammeter (b) voltmeter
24. 24.⚡ A device works on 9 V and takes 0.1 A. What is its power (in watts)? =
25. 25.🔺 A current of 20 mA flows through a 300 Ω resistor. What is the voltage across it (in volts)? =
26. 26.⚡ A home appliance on the 230 V mains takes 0.5 A. What is its power (in watts)?
27. 27.What does a resistor do? (a) has coloured bands (b) blows if current is high (c) boosts a small signal (d) senses how bright it is
28. 28.True or false: to leave the TV on standby saves electricity. (a) False (b) True
29. 29.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 28000 Ω resistor? (a) red-grey-yellow (b) red-grey-orange (c) grey-red-orange (d) red-grey-red
30. 30.🔺 A current of 25 mA flows through a 330 Ω resistor. What is the voltage across it (in volts)? =
31. 31.True or false: an LDR smooths a wobbly supply. (a) False (b) True
32. 32.📏 How many kilowatts (kW) is 2700 W? =
33. 33.True or false: resistance is measured in volts (V). (a) False (b) True
34. 34.⚡ A 2.25 W device works on 1.5 V. What current does it take (in amperes)? =
35. 35.🧩 Which component glows using little power? (a) diode (b) transistor (c) LED (d) capacitor
36. 36.🔺 A current of 0.1 A flows through a 5 Ω resistor. What is the voltage across it (in volts)? =
37. 37.Which of these is measured in amperes (A)? (a) voltage (b) how much a part resists (c) the push of a cell (d) current
38. 38.True or false: on an LED, the shorter leg is the cathode (−). (a) True (b) False
39. 39.🔺 A current of 2.5 A flows through a 6 Ω resistor. What is the voltage across it (in volts)? =
40. 40.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) becomes zero (b) stays the same (c) gets bigger (d) gets smaller

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