Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 485 · 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.True or false: a capacitor smooths a wobbly supply. (a) True (b) False
2. 2.🔺 A current of 50 mA flows through a 300 Ω resistor. What is the voltage across it (in volts)? =
3. 3.📏 How many watts (W) is 1.9 kW?
4. 4.💡 On an LED, is the shorter leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
5. 5.🔺 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
6. 6.🧮 A 68 Ω resistor is joined in series with two equal 200 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
7. 7.💡 Does it save or waste electricity to set the AC to 24 °C? (a) wastes electricity (b) saves electricity
8. 8.🧮 Adding another resistor in series makes the total resistance … (a) zero (b) stay the same (c) smaller (d) bigger
9. 9.🧮 Resistors of 150 Ω and 150 Ω are joined in series. What is the total resistance (in ohms)?
10. 10.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 23000 Ω resistor? (a) orange-red-orange (b) red-orange-orange (c) red-orange-red (d) red-orange-yellow
11. 11.🧩 Which component beeps for an alarm? (a) fuse (b) resistor (c) diode (d) buzzer
12. 12.🔺 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
13. 13.🧾 A family uses 40 units of electricity in a month and each unit costs ₹5. What is the bill (in ₹)?
14. 14.🧮 A 3 V battery is joined to 5 Ω and 10 Ω resistors in series. What current flows (in amperes)? =
15. 15.💡 On an LED, is the round-side leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
16. 16.🔍 Which is the odd one out? (a) use old filament bulbs (b) leave fridge door open (c) leave the TV on standby (d) unplug idle chargers
17. 17.⚡ A 1.5 W device works on 1.5 V. What current does it take (in amperes)? =
18. 18.🧮 Two equal 20 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
19. 19.📏 Which unit measures power? (a) ampere (A) (b) volt (V) (c) ohm (Ω) (d) watt (W)
20. 20.🧮 Resistors of 22 Ω and 100 Ω are joined in series. What is the total resistance (in ohms)?
21. 21.🌈 In the resistor colour code, which number does blue stand for?
22. 22.🧾 A 60 W filament bulb is swapped for a 9 W LED lamp that gives about the same light. Both would run for 1 hour. How many watt-hours (Wh) are saved?
23. 23.🧩 Which component senses how bright it is? (a) potentiometer (b) fuse (c) buzzer (d) LDR
24. 24.⚡ Power tells us … (a) the size of a cell (b) the colour of light (c) the length of a wire (d) energy used each second
25. 25.🔺 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
26. 26.What does a resistor do? (a) senses how bright it is (b) blows if current is high (c) limits the current (d) stores a little charge
27. 27.💡 A red LED uses 2 V and should get 10 mA. It runs from a 9 V supply. What resistor (in ohms) is needed in series?
28. 28.🧮 Resistors of 22 Ω and 33 Ω are joined in series. What is the total resistance (in ohms)?
29. 29.🔺 A current of 0.1 A flows through a 5 Ω resistor. What is the voltage across it (in volts)? =
30. 30.🧾 A 40 W filament bulb is swapped for a 6 W LED lamp that gives about the same light. Both would run for 4 hours. How many watt-hours (Wh) are saved?
31. 31.🌈 A gold fourth band on a resistor means the value may be off by … (a) 25 % (b) 5 % (c) 0 % (d) 50 %
32. 32.📏 How many milliamperes (mA) is 0.99 A?
33. 33.Which of these saves electricity? (a) set the AC to 24 °C (b) leave fridge door open (c) use old filament bulbs (d) iron one shirt at a time
34. 34.🌈 In the resistor colour code, which number does yellow stand for?
35. 35.🔍 Which is the odd one out? (a) unplug idle chargers (b) close the fridge quickly (c) leave fridge door open (d) switch off empty rooms
36. 36.🔺 A current of 20 mA flows when 9.4 V is joined across a resistor. What is its resistance (in ohms)?
37. 37.🧮 A 10 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)?
38. 38.📏 How many ohms (Ω) is 5.3 kΩ?
39. 39.What does a thermistor do? (a) senses how hot it is (b) is a resistance knob (c) turns a fan or wheels (d) limits the current
40. 40.🧾 Which lamp gives the same light for the least power? (a) a candle (b) a filament bulb (c) an LED lamp (d) an oil lamp

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