Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 569 · 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 current of 1 A flows through a 3 Ω resistor. What is the voltage across it (in volts)? =
2. 2.💡 What does LED stand for? (a) light energy dial (b) large electric dial (c) low energy device (d) light-emitting diode
3. 3.🧾 A family uses 110 units of electricity in a month and each unit costs ₹9. What is the bill (in ₹)?
4. 4.🔺 A current of 10 mA flows through a 100 Ω resistor. What is the voltage across it (in volts)? =
5. 5.🧩 A capacitor in a circuit can … (a) measure heat (b) spin a wheel (c) store charge briefly (d) make light
6. 6.💡 On an LED, is the round-side leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
7. 7.💡 On an LED, is the shorter leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
8. 8.🔺 A current of 2.5 A flows when 37.5 V is joined across a resistor. What is its resistance (in ohms)?
9. 9.💡 Why does an LED need a resistor in series? (a) to change its colour (b) to store charge (c) to limit the current (d) to make it brighter
10. 10.🔺 A current of 10 mA flows when 4.7 V is joined across a resistor. What is its resistance (in ohms)?
11. 11.🔺 A current of 25 mA flows through a 250 Ω resistor. What is the voltage across it (in volts)? =
12. 12.📏 How many kilo-ohms (kΩ) is 900 Ω? =
13. 13.🧮 A 1.5 V battery is joined to 10 Ω and 5 Ω resistors in series. What current flows (in amperes)? =
14. 14.⚡ A 15 W device works on 5 V. What current does it take (in amperes)? =
15. 15.🧩 Which component stores a little charge? (a) resistor (b) capacitor (c) buzzer (d) LDR
16. 16.🔺 A 3.3 V supply is joined across a 330 Ω resistor. What current flows (in milliamperes, mA)?
17. 17.📏 Which unit measures energy used each second? (a) ohm (Ω) (b) ampere (A) (c) watt (W) (d) volt (V)
18. 18.🧩 Which component blows if current is high? (a) thermistor (b) motor (c) potentiometer (d) fuse
19. 19.🌈 A resistor has the colour bands yellow, brown, yellow. What is its value in kilo-ohms (kΩ)? =
20. 20.🔺 A current of 50 mA flows when 16.5 V is joined across a resistor. What is its resistance (in ohms)?
21. 21.🧩 Which part changes electrical energy into sound? (a) a capacitor (b) a resistor (c) a diode (d) a buzzer
22. 22.🌈 A resistor has the colour bands violet, yellow, black. What is its value (in ohms)?
23. 23.🧮 Three equal 150 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
24. 24.📏 Which unit measures the flow of charge? (a) volt (V) (b) ohm (Ω) (c) watt (W) (d) ampere (A)
25. 25.💡 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) may burn out (b) does not light (c) lights up
26. 26.⚡ A home appliance on the 230 V mains takes 4 A. What is its power (in watts)?
27. 27.Which of these is measured in watts (W)? (a) current (b) voltage (c) the push of a cell (d) energy used each second
28. 28.💡 Does it save or waste electricity to set the AC to 24 °C? (a) saves electricity (b) wastes electricity
29. 29.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark an 87000 Ω resistor? (a) grey-violet-yellow (b) grey-violet-orange (c) violet-grey-orange (d) grey-violet-red
30. 30.True or false: the voltmeter measures current. (a) True (b) False
31. 31.🔺 A current of 25 mA flows through a 400 Ω resistor. What is the voltage across it (in volts)? =
32. 32.Which of these wastes electricity? (a) leave fridge door open (b) set the AC to 24 °C (c) use daylight to read (d) unplug idle chargers
33. 33.🔺 A current of 40 mA flows through a 250 Ω resistor. What is the voltage across it (in volts)? =
34. 34.🔺 In the V-I-R triangle, how do we find I? (a) I = V × R (b) I = R ÷ V (c) I = V ÷ R (d) I = V + R
35. 35.🔺 A 10 V supply is joined across a 250 Ω resistor. What current flows (in milliamperes, mA)?
36. 36.True or false: how much a part resists is measured in amperes (A). (a) True (b) False
37. 37.True or false: on an LED, the leg by the flat edge is the anode (+). (a) False (b) True
38. 38.🌈 A resistor has the colour bands white, yellow, orange. What is its value in kilo-ohms (kΩ)? =
39. 39.True or false: on an LED, the shorter leg is the anode (+). (a) False (b) True
40. 40.💡 Does it save or waste electricity to use LED lamps? (a) wastes electricity (b) saves electricity

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