Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 43 · 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.📏 How many kilo-ohms (kΩ) is 5100 Ω? =
2. 2.💡 Why does an LED need a resistor in series? (a) to limit the current (b) to store charge (c) to make it brighter (d) to change its colour
3. 3.📏 How many kilowatts (kW) is 2850 W? =
4. 4.🧮 Two resistors in parallel give a total that is … (a) always zero (b) more than either one (c) their sum (d) less than either one
5. 5.🧮 Two equal 100 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
6. 6.💡 What does LED stand for? (a) light energy dial (b) large electric dial (c) low energy device (d) light-emitting diode
7. 7.🔺 A current of 0.1 A flows through a 20 Ω resistor. What is the voltage across it (in volts)? =
8. 8.📏 Voltmeter or ammeter: which one is joined across a part? (a) ammeter (b) voltmeter
9. 9.🔺 A current of 2 A flows through a 5 Ω resistor. What is the voltage across it (in volts)? =
10. 10.🔺 A current of 40 mA flows when 18.8 V is joined across a resistor. What is its resistance (in ohms)?
11. 11.🧮 Two equal 40 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
12. 12.🔺 In the V-I-R triangle, how do we find V? (a) V = I ÷ R (b) V = R ÷ I (c) V = I + R (d) V = I × R
13. 13.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) gets smaller (b) gets bigger (c) becomes zero (d) stays the same
14. 14.🔺 A current of 50 mA flows through a 200 Ω resistor. What is the voltage across it (in volts)? =
15. 15.🔺 A 3 V supply is joined across a 3 Ω resistor. What current flows (in amperes)? =
16. 16.🔺 A current of 50 mA flows through a 470 Ω resistor. What is the voltage across it (in volts)? =
17. 17.What does a buzzer do? (a) is a resistance knob (b) limits the current (c) makes things spin (d) beeps for an alarm
18. 18.💡 An LED is joined to a 6 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
19. 19.🌈 Which band is read first on a resistor? (a) the gold band (b) the one nearest an end (c) any band (d) the widest gap
20. 20.True or false: a diode lets current go one way. (a) True (b) False
21. 21.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 62 Ω resistor? (a) blue-red-brown (b) blue-red-black (c) red-blue-black (d) violet-red-black
22. 22.💡 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)?
23. 23.⚡ A home appliance on the 230 V mains takes 5 A. What is its power (in watts)?
24. 24.Which of these is measured in amperes (A)? (a) the flow of charge (b) how much a part resists (c) energy used each second (d) voltage
25. 25.🧾 A 40 W filament bulb is swapped for a 6 W LED lamp that gives about the same light. Both would run for 7 hours. How many watt-hours (Wh) are saved?
26. 26.📏 How many kilo-ohms (kΩ) is 1600 Ω? =
27. 27.📏 How many watts (W) is 2.7 kW?
28. 28.True or false: the ammeter measures voltage. (a) False (b) True
29. 29.True or false: to use LED lamps saves electricity. (a) False (b) True
30. 30.📏 Which unit measures how much a part resists? (a) volt (V) (b) ohm (Ω) (c) ampere (A) (d) watt (W)
31. 31.🔺 A current of 20 mA flows through a 200 Ω resistor. What is the voltage across it (in volts)? =
32. 32.🧩 Which part changes electrical energy into sound? (a) a diode (b) a capacitor (c) a resistor (d) a buzzer
33. 33.📏 Voltmeter or ammeter: which one measures voltage? (a) ammeter (b) voltmeter
34. 34.What does a buzzer do? (a) smooths a wobbly supply (b) makes a beeping sound (c) has coloured bands (d) turns a fan or wheels
35. 35.📏 How many ohms (Ω) is 6.7 kΩ?
36. 36.True or false: voltage is measured in volts (V). (a) False (b) True
37. 37.True or false: a transistor stores a little charge. (a) True (b) False
38. 38.🧮 Two equal 330 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
39. 39.💡 A red LED uses 2 V and should get 20 mA. It runs from a 5 V supply. What resistor (in ohms) is needed in series?
40. 40.🔺 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

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