Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 223 · 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 device works on 6 V and takes 0.5 A. What is its power (in watts)? =
2. 2.True or false: the voltmeter measures current. (a) False (b) True
3. 3.📏 Voltmeter or ammeter: which one measures voltage? (a) ammeter (b) voltmeter
4. 4.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 40000 Ω resistor? (a) green-yellow-orange (b) yellow-black-red (c) yellow-black-orange (d) yellow-black-yellow
5. 5.🌈 Which band is read first on a resistor? (a) any band (b) the one nearest an end (c) the widest gap (d) the gold band
6. 6.🔺 A current of 10 mA flows when 1.2 V is joined across a resistor. What is its resistance (in ohms)?
7. 7.📏 In the water-pipe picture of a circuit, resistance is like … (a) a bigger tank (b) a narrow pipe (c) the water pressure (d) the flow of water
8. 8.🔺 A current of 40 mA flows through a 220 Ω resistor. What is the voltage across it (in volts)? =
9. 9.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) stays the same (b) gets bigger (c) becomes zero (d) gets smaller
10. 10.💡 An LED is joined to a 9 V battery through a 330 Ω 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
11. 11.🧾 A 100 W filament bulb is swapped for a 15 W LED lamp that gives about the same light. Both would run for 10 hours. How many watt-hours (Wh) are saved?
12. 12.💡 A red LED (it uses 2 V) is joined with a 100 Ω resistor to a 2.5 V supply. What current flows (in mA)?
13. 13.Which of these is measured in volts (V)? (a) voltage (b) how much a part resists (c) current (d) resistance
14. 14.🔍 Which is the odd one out? (a) set the AC to 24 °C (b) leave the TV on standby (c) unplug idle chargers (d) use LED lamps
15. 15.⚡ A 6 W device works on 3 V. What current does it take (in amperes)? =
16. 16.📏 Voltmeter or ammeter: which one measures current? (a) ammeter (b) voltmeter
17. 17.True or false: to iron one shirt at a time wastes electricity. (a) False (b) True
18. 18.⚡ Which formula gives electric power? (a) P = I ÷ V (b) P = V × I (c) P = V ÷ I (d) P = V + I
19. 19.📏 How many kilo-ohms (kΩ) is 2500 Ω? =
20. 20.🔺 A current of 20 mA flows through a 200 Ω resistor. What is the voltage across it (in volts)? =
21. 21.📏 Voltmeter or ammeter: which one is joined in series? (a) voltmeter (b) ammeter
22. 22.🧮 Three equal 75 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
23. 23.Which of these wastes electricity? (a) leave fridge door open (b) close the fridge quickly (c) set the AC to 24 °C (d) use LED lamps
24. 24.True or false: a capacitor boosts a small signal. (a) True (b) False
25. 25.True or false: the voltmeter is joined in series. (a) True (b) False
26. 26.🧩 A capacitor in a circuit can … (a) store charge briefly (b) spin a wheel (c) make light (d) measure heat
27. 27.🔺 A current of 1.5 A flows through a 10 Ω resistor. What is the voltage across it (in volts)? =
28. 28.🌈 A resistor has the colour bands red, white, yellow. What is its value in kilo-ohms (kΩ)? =
29. 29.🔺 A current of 0.25 A flows when 5 V is joined across a resistor. What is its resistance (in ohms)?
30. 30.💡 On an LED, is the longer leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
31. 31.🧮 Resistors of 150 Ω, 68 Ω, 22 Ω and 33 Ω are joined in series. What is the total resistance (in ohms)?
32. 32.📏 How many amperes (A) is 2300 mA? =
33. 33.🔺 In the V-I-R triangle, how do we find R? (a) R = V + I (b) R = V ÷ I (c) R = I ÷ V (d) R = V × I
34. 34.🔺 A current of 0.5 A flows through a 12 Ω resistor. What is the voltage across it (in volts)? =
35. 35.🧾 A family uses 70 units of electricity in a month and each unit costs ₹6. What is the bill (in ₹)?
36. 36.💡 A red LED uses 2 V and should get 20 mA. It runs from a 6 V supply. What resistor (in ohms) is needed in series?
37. 37.🧾 A 500 W appliance runs for 8 hours. How many units (kWh) of electricity does it use? =
38. 38.🔺 A current of 20 mA flows through a 300 Ω resistor. What is the voltage across it (in volts)? =
39. 39.🔺 A 7.5 V supply is joined across a 15 Ω resistor. What current flows (in amperes)? =
40. 40.📏 Which unit measures voltage? (a) ampere (A) (b) ohm (Ω) (c) watt (W) (d) volt (V)

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