Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 901 · 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 device works on 3 V and takes 0.2 A. What is its power (in watts)? =
2. 2.Which of these is measured in amperes (A)? (a) resistance (b) energy used each second (c) the flow of charge (d) voltage
3. 3.⚡ Which formula gives electric power? (a) P = I ÷ V (b) P = V + I (c) P = V × I (d) P = V ÷ I
4. 4.🧾 Which lamp gives the same light for the least power? (a) an oil lamp (b) an LED lamp (c) a filament bulb (d) a candle
5. 5.What does a capacitor do? (a) limits the current (b) lets current go one way (c) is a resistance knob (d) smooths a wobbly supply
6. 6.True or false: an LDR senses how bright it is. (a) False (b) True
7. 7.🧮 A 100 Ω resistor is joined in series with two equal 330 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
8. 8.⚡ A device works on 5 V and takes 0.25 A. What is its power (in watts)? =
9. 9.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 75000 Ω resistor? (a) green-violet-orange (b) violet-green-orange (c) violet-green-red (d) violet-green-yellow
10. 10.True or false: the flow of charge is measured in ohms (Ω). (a) False (b) True
11. 11.⚡ A home appliance on the 230 V mains takes 8 A. What is its power (in watts)?
12. 12.🧮 Two resistors in parallel give a total that is … (a) more than either one (b) their sum (c) always zero (d) less than either one
13. 13.🔺 In the V-I-R triangle, how do we find R? (a) R = V ÷ I (b) R = V + I (c) R = I ÷ V (d) R = V × I
14. 14.📏 How many amperes (A) is 660 mA? =
15. 15.🔺 A current of 20 mA flows through a 400 Ω resistor. What is the voltage across it (in volts)? =
16. 16.📏 Voltmeter or ammeter: which one is joined in series? (a) voltmeter (b) ammeter
17. 17.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 57000 Ω resistor? (a) green-violet-yellow (b) violet-green-orange (c) green-violet-red (d) green-violet-orange
18. 18.True or false: on an LED, the leg by the flat edge is the cathode (−). (a) True (b) False
19. 19.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) gets bigger (b) gets smaller (c) becomes zero (d) stays the same
20. 20.🌈 A resistor has the colour bands white, grey, orange. What is its value in kilo-ohms (kΩ)? =
21. 21.🧮 Five equal 100 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
22. 22.🌈 A resistor has the colour bands blue, white, orange. What is its value (in ohms)?
23. 23.⚡ Power tells us … (a) the size of a cell (b) the length of a wire (c) the colour of light (d) energy used each second
24. 24.True or false: on an LED, the longer leg is the anode (+). (a) True (b) False
25. 25.🧩 Which component limits the current? (a) buzzer (b) thermistor (c) diode (d) resistor
26. 26.🧮 Adding another resistor in series makes the total resistance … (a) smaller (b) stay the same (c) bigger (d) zero
27. 27.🧩 A capacitor in a circuit can … (a) measure heat (b) spin a wheel (c) store charge briefly (d) make light
28. 28.⚡ A device works on 5 V and takes 0.5 A. What is its power (in watts)? =
29. 29.True or false: a potentiometer lets current go one way. (a) True (b) False
30. 30.🔺 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
31. 31.True or false: on an LED, the shorter leg is the cathode (−). (a) True (b) False
32. 32.💡 On an LED, is the shorter leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
33. 33.🧮 A 470 Ω resistor is joined in series with two equal 40 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
34. 34.💡 A red LED (it uses 2 V) is joined with a 300 Ω resistor to an 8 V supply. What current flows (in mA)?
35. 35.🔺 A current of 40 mA flows through a 470 Ω resistor. What is the voltage across it (in volts)? =
36. 36.🌈 In the resistor colour code, which number does orange stand for?
37. 37.🔺 A current of 20 mA flows when 4.4 V is joined across a resistor. What is its resistance (in ohms)?
38. 38.🧾 A family uses 40 units of electricity in a month and each unit costs ₹5. What is the bill (in ₹)?
39. 39.🧩 Which part changes electrical energy into movement? (a) an LED (b) a resistor (c) a motor (d) a fuse
40. 40.True or false: an LDR senses how hot it is. (a) False (b) True

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