Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 301 · 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.🧩 Which component has coloured bands? (a) LDR (b) LED (c) buzzer (d) resistor
2. 2.🧾 A 50 W appliance runs for 2 hours. How many units (kWh) of electricity does it use? =
3. 3.🔺 A current of 20 mA flows through a 220 Ω resistor. What is the voltage across it (in volts)? =
4. 4.🔺 A current of 25 mA flows through a 330 Ω resistor. What is the voltage across it (in volts)? =
5. 5.🔺 A current of 50 mA flows through a 400 Ω resistor. What is the voltage across it (in volts)? =
6. 6.⚡ A device works on 12 V and takes 0.5 A. What is its power (in watts)? =
7. 7.True or false: to switch off empty rooms saves electricity. (a) False (b) True
8. 8.🔺 A 3.75 V supply is joined across a 150 Ω resistor. What current flows (in milliamperes, mA)?
9. 9.🌈 A gold fourth band on a resistor means the value may be off by … (a) 50 % (b) 25 % (c) 5 % (d) 0 %
10. 10.🧾 A family uses 180 units of electricity in a month and each unit costs ₹7. What is the bill (in ₹)?
11. 11.🧮 A 20 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)?
12. 12.🧮 Four equal 400 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
13. 13.📏 Voltmeter or ammeter: which one measures voltage? (a) ammeter (b) voltmeter
14. 14.What does a thermistor do? (a) has coloured bands (b) limits the current (c) senses how hot it is (d) makes a beeping sound
15. 15.🧩 Which component senses how bright it is? (a) buzzer (b) LDR (c) transistor (d) potentiometer
16. 16.💡 An LED is joined to a 3 V battery through a 220 Ω resistor; the leg next to the flat edge of its rim goes to the + side. What happens? (a) lights up (b) may burn out (c) does not light
17. 17.True or false: a resistor stores a little charge. (a) False (b) True
18. 18.True or false: to close the fridge quickly wastes electricity. (a) True (b) False
19. 19.🧾 A 50 W appliance runs for 5 hours. How many units (kWh) of electricity does it use? =
20. 20.True or false: to use LED lamps saves electricity. (a) False (b) True
21. 21.Which of these saves electricity? (a) run fans in empty rooms (b) use old filament bulbs (c) use LED lamps (d) leave fridge door open
22. 22.True or false: a transistor lets current go one way. (a) False (b) True
23. 23.Which of these is measured in watts (W)? (a) current (b) the flow of charge (c) resistance (d) energy used each second
24. 24.💡 A red LED (it uses 2 V) is joined with a 300 Ω resistor to a 6.5 V supply. What current flows (in mA)?
25. 25.🔺 In the V-I-R triangle, how do we find V? (a) V = I + R (b) V = I × R (c) V = I ÷ R (d) V = R ÷ I
26. 26.💡 On an LED, is the longer leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
27. 27.🧮 Three equal 150 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
28. 28.🔺 A current of 10 mA flows through a 500 Ω resistor. What is the voltage across it (in volts)? =
29. 29.💡 Does it save or waste electricity to use daylight to read? (a) saves electricity (b) wastes electricity
30. 30.📏 How many kilo-ohms (kΩ) is 2200 Ω? =
31. 31.🧮 Resistors of 330 Ω and 47 Ω are joined in series. What is the total resistance (in ohms)?
32. 32.What does a resistor do? (a) stores a little charge (b) makes things spin (c) boosts a small signal (d) limits the current
33. 33.🔺 A 6.25 V supply is joined across a 250 Ω resistor. What current flows (in milliamperes, mA)?
34. 34.⚡ A 4.5 W device works on 9 V. What current does it take (in amperes)? =
35. 35.True or false: a motor makes things spin. (a) True (b) False
36. 36.Which of these is measured in ohms (Ω)? (a) the flow of charge (b) power (c) resistance (d) the push of a cell
37. 37.🔺 A current of 20 mA flows through a 470 Ω resistor. What is the voltage across it (in volts)? =
38. 38.🔺 A current of 1.5 A flows through a 10 Ω resistor. What is the voltage across it (in volts)? =
39. 39.⚡ A 1.8 W device works on 9 V. What current does it take (in amperes)? =
40. 40.💡 An LED is joined to a 5 V battery through a 220 Ω resistor; the leg next to the flat edge of its rim goes to the − side. What happens? (a) lights up (b) does not light (c) may burn out

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