Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 326 · 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 12 W device works on 6 V. What current does it take (in amperes)? =
2. 2.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 750 Ω resistor? (a) violet-green-brown (b) violet-green-red (c) violet-green-black (d) green-violet-brown
3. 3.🧩 Which component makes things spin? (a) buzzer (b) motor (c) capacitor (d) diode
4. 4.🔺 A current of 25 mA flows when 2.5 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) anode (+) (b) cathode (−)
6. 6.🧮 A 6 V battery is joined to 2 Ω and 4 Ω resistors in series. What current flows (in amperes)? =
7. 7.📏 Which unit measures the flow of charge? (a) ampere (A) (b) watt (W) (c) volt (V) (d) ohm (Ω)
8. 8.💡 Does it save or waste electricity to use LED lamps? (a) saves electricity (b) wastes electricity
9. 9.🌈 A gold fourth band on a resistor means the value may be off by … (a) 25 % (b) 0 % (c) 5 % (d) 50 %
10. 10.🧾 A family uses 140 units of electricity in a month and each unit costs ₹8. What is the bill (in ₹)?
11. 11.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) becomes zero (b) gets bigger (c) stays the same (d) gets smaller
12. 12.🧮 Four equal 40 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
13. 13.🔺 A current of 1.5 A flows through a 20 Ω resistor. What is the voltage across it (in volts)? =
14. 14.🧮 Resistors of 10 Ω, 33 Ω, 470 Ω and 50 Ω are joined in series. What is the total resistance (in ohms)?
15. 15.🌈 In the resistor colour code, which number does brown stand for?
16. 16.💡 On an LED, is the round-side leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
17. 17.🔍 Which is the odd one out? (a) leave the TV on standby (b) close the fridge quickly (c) run fans in empty rooms (d) use old filament bulbs
18. 18.💡 An LED is joined to a 3 V battery through a 470 Ω resistor; its long leg goes to the − side and its short leg to the + side. What happens? (a) does not light (b) lights up (c) may burn out
19. 19.True or false: on an LED, the longer leg is the cathode (−). (a) False (b) True
20. 20.💡 Does it save or waste electricity to use daylight to read? (a) saves electricity (b) wastes electricity
21. 21.⚡ A device works on 9 V and takes 3 A. What is its power (in watts)? =
22. 22.⚡ Power tells us … (a) the colour of light (b) the size of a cell (c) the length of a wire (d) energy used each second
23. 23.🔺 A current of 10 mA flows through a 400 Ω resistor. What is the voltage across it (in volts)? =
24. 24.🔺 A current of 0.25 A flows through a 4 Ω resistor. What is the voltage across it (in volts)? =
25. 25.🧾 A 100 W filament bulb is swapped for a 15 W LED lamp that gives about the same light. Both would run for 1 hour. How many watt-hours (Wh) are saved?
26. 26.🌈 A resistor has the colour bands violet, blue, black. What is its value (in ohms)?
27. 27.💡 An LED is joined to a 9 V battery with no resistor; its long leg goes to the + side and its short leg to the − side. What happens? (a) may burn out (b) lights up (c) does not light
28. 28.🔺 A current of 50 mA flows when 11 V is joined across a resistor. What is its resistance (in ohms)?
29. 29.🌈 Which band is read first on a resistor? (a) the gold band (b) the one nearest an end (c) any band (d) the widest gap
30. 30.🌈 A resistor has the colour bands yellow, brown, red. What is its value (in ohms)?
31. 31.🔺 A current of 1 A flows through a 12 Ω resistor. What is the voltage across it (in volts)? =
32. 32.⚡ A 2.25 W device works on 1.5 V. What current does it take (in amperes)? =
33. 33.🧮 A 50 Ω resistor is joined in series with two equal 50 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
34. 34.Which of these wastes electricity? (a) use daylight to read (b) switch off empty rooms (c) set the AC to 24 °C (d) leave the TV on standby
35. 35.🧮 Five equal 250 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
36. 36.💡 A red LED (it uses 2 V) is joined with a 100 Ω resistor to a 3 V supply. What current flows (in mA)?
37. 37.True or false: on an LED, the round-side leg is the anode (+). (a) True (b) False
38. 38.⚡ A 24 W device works on 12 V. What current does it take (in amperes)? =
39. 39.Which of these is measured in volts (V)? (a) resistance (b) the flow of charge (c) energy used each second (d) the push of a cell
40. 40.🔺 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

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