Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 888 · 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 3 A flows through a 4 Ω resistor. What is the voltage across it (in volts)? =
2. 2.💡 Does it save or waste electricity to use LED lamps? (a) wastes electricity (b) saves electricity
3. 3.📏 How many kilowatts (kW) is 2000 W? =
4. 4.🧩 Which component makes a beeping sound? (a) motor (b) buzzer (c) capacitor (d) resistor
5. 5.⚡ Which formula gives electric power? (a) P = V ÷ I (b) P = V + I (c) P = V × I (d) P = I ÷ V
6. 6.💡 What happens if an LED is put in backwards? (a) it changes colour (b) it makes a sound (c) it does not light (d) it lights brighter
7. 7.🧾 A 500 W appliance runs for 10 hours. How many units (kWh) of electricity does it use? =
8. 8.🔺 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
9. 9.🧩 Which part changes electrical energy into movement? (a) an LED (b) a fuse (c) a resistor (d) a motor
10. 10.🧮 Two equal 470 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
11. 11.⚡ A device works on 5 V and takes 0.2 A. What is its power (in watts)? =
12. 12.🌈 A resistor has the colour bands orange, orange, red. What is its value (in ohms)?
13. 13.🔺 A current of 20 mA flows through a 220 Ω resistor. What is the voltage across it (in volts)? =
14. 14.💡 Does it save or waste electricity to switch off empty rooms? (a) wastes electricity (b) saves electricity
15. 15.💡 What does LED stand for? (a) large electric dial (b) low energy device (c) light-emitting diode (d) light energy dial
16. 16.🧩 Which part changes electrical energy into sound? (a) a resistor (b) a buzzer (c) a diode (d) a capacitor
17. 17.🔺 A current of 1 A flows through a 6 Ω resistor. What is the voltage across it (in volts)? =
18. 18.🔺 A current of 0.2 A flows through a 20 Ω resistor. What is the voltage across it (in volts)? =
19. 19.🔺 A current of 0.2 A flows through a 15 Ω resistor. What is the voltage across it (in volts)? =
20. 20.🧮 Two resistors in parallel give a total that is … (a) their sum (b) more than either one (c) always zero (d) less than either one
21. 21.⚡ A home appliance on the 230 V mains takes 0.5 A. What is its power (in watts)?
22. 22.🔺 A current of 0.2 A flows when 0.6 V is joined across a resistor. What is its resistance (in ohms)?
23. 23.🌈 A gold fourth band on a resistor means the value may be off by … (a) 5 % (b) 50 % (c) 25 % (d) 0 %
24. 24.💡 An LED is joined to a 6 V battery through a 330 Ω resistor; the leg next to the flat edge of its rim goes to the + side. What happens? (a) does not light (b) may burn out (c) lights up
25. 25.💡 On an LED, is the longer leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
26. 26.📏 How many milliamperes (mA) is 2.52 A?
27. 27.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 4000 Ω resistor? (a) yellow-black-red (b) yellow-black-brown (c) yellow-black-orange (d) green-yellow-red
28. 28.True or false: a capacitor makes a beeping sound. (a) False (b) True
29. 29.True or false: a diode lets current go one way. (a) False (b) True
30. 30.💡 Does it save or waste electricity to use daylight to read? (a) wastes electricity (b) saves electricity
31. 31.🔺 A current of 50 mA flows when 15 V is joined across a resistor. What is its resistance (in ohms)?
32. 32.📏 How many milliamperes (mA) is 2.22 A?
33. 33.🌈 Which band is read first on a resistor? (a) the gold band (b) any band (c) the one nearest an end (d) the widest gap
34. 34.🔺 A current of 10 mA flows through a 220 Ω resistor. What is the voltage across it (in volts)? =
35. 35.📏 Which unit measures energy used each second? (a) ampere (A) (b) ohm (Ω) (c) volt (V) (d) watt (W)
36. 36.💡 Does it save or waste electricity to leave the TV on standby? (a) wastes electricity (b) saves electricity
37. 37.True or false: the push of a cell is measured in volts (V). (a) True (b) False
38. 38.🧾 A 40 W filament bulb is swapped for a 6 W LED lamp that gives about the same light. Both would run for 1 hour. How many watt-hours (Wh) are saved?
39. 39.🧮 Two equal 220 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
40. 40.Which of these is measured in amperes (A)? (a) energy used each second (b) the flow of charge (c) how much a part resists (d) resistance

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