Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 746 · 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 resistor has the colour bands yellow, black, red. What is its value in kilo-ohms (kΩ)? =
2. 2.Which of these is measured in amperes (A)? (a) voltage (b) how much a part resists (c) resistance (d) the flow of charge
3. 3.🧾 A family uses 70 units of electricity in a month and each unit costs ₹8. What is the bill (in ₹)?
4. 4.Which of these wastes electricity? (a) use LED lamps (b) leave fridge door open (c) set the AC to 24 °C (d) close the fridge quickly
5. 5.True or false: on an LED, the longer leg is the anode (+). (a) True (b) False
6. 6.⚡ Power tells us … (a) the length of a wire (b) the colour of light (c) energy used each second (d) the size of a cell
7. 7.🔺 An 8.25 V supply is joined across a 330 Ω resistor. What current flows (in milliamperes, mA)?
8. 8.📏 Which unit measures voltage? (a) volt (V) (b) watt (W) (c) ohm (Ω) (d) ampere (A)
9. 9.💡 What does LED stand for? (a) low energy device (b) light energy dial (c) light-emitting diode (d) large electric dial
10. 10.💡 On an LED, is the shorter leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
11. 11.Which of these is measured in ohms (Ω)? (a) resistance (b) energy used each second (c) power (d) the push of a cell
12. 12.🧮 Resistors of 22 Ω, 220 Ω, 150 Ω and 470 Ω are joined in series. What is the total resistance (in ohms)?
13. 13.💡 Does it save or waste electricity to run fans in empty rooms? (a) wastes electricity (b) saves electricity
14. 14.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) gets smaller (b) becomes zero (c) gets bigger (d) stays the same
15. 15.🧩 A capacitor in a circuit can … (a) make light (b) measure heat (c) store charge briefly (d) spin a wheel
16. 16.🧾 A family uses 80 units of electricity in a month and each unit costs ₹7. What is the bill (in ₹)?
17. 17.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 4500 Ω resistor? (a) green-yellow-red (b) yellow-green-orange (c) yellow-green-brown (d) yellow-green-red
18. 18.🧩 Which component makes a beeping sound? (a) motor (b) potentiometer (c) buzzer (d) LDR
19. 19.🔺 A current of 0.5 A flows when 4 V is joined across a resistor. What is its resistance (in ohms)?
20. 20.📏 Voltmeter or ammeter: which one measures current? (a) ammeter (b) voltmeter
21. 21.What does a thermistor do? (a) beeps for an alarm (b) smooths a wobbly supply (c) is a resistance knob (d) senses how hot it is
22. 22.⚡ A 72 W device works on 24 V. What current does it take (in amperes)? =
23. 23.💡 On an LED, is the round-side leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
24. 24.📏 How many kilowatts (kW) is 2950 W? =
25. 25.🌈 A gold fourth band on a resistor means the value may be off by … (a) 5 % (b) 25 % (c) 50 % (d) 0 %
26. 26.🧮 Resistors of 10 Ω, 470 Ω and 330 Ω are joined in series. What is the total resistance (in ohms)?
27. 27.💡 A blue LED uses 3 V and should get 20 mA. It runs from a 12 V supply. What resistor (in ohms) is needed in series?
28. 28.⚡ A home appliance on the 230 V mains takes 0.5 A. What is its power (in watts)?
29. 29.🌈 A resistor has the colour bands yellow, red, red. What is its value in kilo-ohms (kΩ)? =
30. 30.🔺 A current of 3 A flows through a 20 Ω resistor. What is the voltage across it (in volts)? =
31. 31.🔺 A current of 10 mA flows through a 250 Ω resistor. What is the voltage across it (in volts)? =
32. 32.🧮 Four equal 40 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
33. 33.True or false: on an LED, the leg by the flat edge is the cathode (−). (a) False (b) True
34. 34.What does a potentiometer do? (a) senses how bright it is (b) lets current go one way (c) is a resistance knob (d) smooths a wobbly supply
35. 35.🌈 In the resistor colour code, which number does blue stand for?
36. 36.🧩 Which part changes electrical energy into sound? (a) a diode (b) a buzzer (c) a capacitor (d) a resistor
37. 37.💡 An LED is joined to a 6 V battery through a 470 Ω resistor; the leg next to the flat edge of its rim goes to the + side. What happens? (a) may burn out (b) does not light (c) lights up
38. 38.🧮 Three equal 15 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
39. 39.💡 A blue LED uses 3 V and should get 10 mA. It runs from a 6 V supply. What resistor (in ohms) is needed in series?
40. 40.🔺 A current of 0.25 A flows through a 3 Ω resistor. What is the voltage across it (in volts)? =

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