Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 232 · 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.What does a capacitor do? (a) has coloured bands (b) glows using little power (c) stores a little charge (d) beeps for an alarm
2. 2.🔺 In the V-I-R triangle, how do we find R? (a) R = V × I (b) R = I ÷ V (c) R = V + I (d) R = V ÷ I
3. 3.🔺 A current of 50 mA flows through a 200 Ω resistor. What is the voltage across it (in volts)? =
4. 4.🧮 Resistors of 330 Ω, 330 Ω, 10 Ω and 470 Ω are joined in series. What is the total resistance (in ohms)?
5. 5.🌈 A resistor has the colour bands red, green, brown. What is its value (in ohms)?
6. 6.🧾 A 75 W filament bulb is swapped for a 12 W LED lamp that gives about the same light. Both would run for 2 hours. How many watt-hours (Wh) are saved?
7. 7.📏 How many kilowatts (kW) is 550 W? =
8. 8.Which of these is measured in volts (V)? (a) energy used each second (b) resistance (c) the flow of charge (d) voltage
9. 9.Which of these saves electricity? (a) use old filament bulbs (b) leave the TV on standby (c) iron one shirt at a time (d) switch off empty rooms
10. 10.What does a transistor do? (a) is a resistance knob (b) boosts a small signal (c) limits the current (d) turns a fan or wheels
11. 11.🔺 A 10 V supply is joined across a 5 Ω resistor. What current flows (in amperes)? =
12. 12.🧮 A 2.4 V battery is joined to 8 Ω and 4 Ω resistors in series. What current flows (in amperes)? =
13. 13.🔺 A 15 V supply is joined across a 15 Ω resistor. What current flows (in amperes)? =
14. 14.🧩 Which component smooths a wobbly supply? (a) capacitor (b) diode (c) resistor (d) LED
15. 15.🔺 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
16. 16.💡 On an LED, is the shorter leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
17. 17.🔺 A current of 2.5 A flows through a 4 Ω resistor. What is the voltage across it (in volts)? =
18. 18.📏 Which unit measures how much a part resists? (a) ohm (Ω) (b) ampere (A) (c) volt (V) (d) watt (W)
19. 19.🧮 Four equal 20 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
20. 20.🧾 A 100 W filament bulb is swapped for a 15 W LED lamp that gives about the same light. Both would run for 3 hours. How many watt-hours (Wh) are saved?
21. 21.🌈 In the resistor colour code, which number does red stand for?
22. 22.True or false: to close the fridge quickly wastes electricity. (a) False (b) True
23. 23.📏 Which unit measures power? (a) ohm (Ω) (b) ampere (A) (c) watt (W) (d) volt (V)
24. 24.⚡ Power tells us … (a) energy used each second (b) the size of a cell (c) the length of a wire (d) the colour of light
25. 25.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 6900 Ω resistor? (a) white-blue-red (b) blue-white-brown (c) blue-white-orange (d) blue-white-red
26. 26.💡 A red LED uses 2 V and should get 10 mA. It runs from a 9 V supply. What resistor (in ohms) is needed in series?
27. 27.🔺 In the V-I-R triangle, how do we find I? (a) I = R ÷ V (b) I = V + R (c) I = V × R (d) I = V ÷ R
28. 28.🔺 A current of 0.1 A flows when 0.4 V is joined across a resistor. What is its resistance (in ohms)?
29. 29.🔺 A 50 V supply is joined across a 20 Ω resistor. What current flows (in amperes)? =
30. 30.🔺 A 24 V supply is joined across an 8 Ω resistor. What current flows (in amperes)? =
31. 31.🔺 A current of 10 mA flows through a 300 Ω resistor. What is the voltage across it (in volts)? =
32. 32.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 7000 Ω resistor? (a) violet-black-red (b) violet-black-brown (c) grey-violet-red (d) violet-black-orange
33. 33.True or false: an LDR blows if current is high. (a) False (b) True
34. 34.🌈 A resistor has the colour bands orange, green, black. What is its value (in ohms)?
35. 35.🧮 Two equal 220 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
36. 36.Which of these is measured in amperes (A)? (a) how much a part resists (b) current (c) power (d) resistance
37. 37.🧩 Which component senses how hot it is? (a) capacitor (b) thermistor (c) buzzer (d) resistor
38. 38.⚡ A home appliance on the 230 V mains takes 1.5 A. What is its power (in watts)?
39. 39.🔺 A 6 V supply is joined across a 120 Ω resistor. What current flows (in milliamperes, mA)?
40. 40.🌈 A resistor has the colour bands grey, brown, brown. What is its value (in ohms)?

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