Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 467 · 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.🌈 In the resistor colour code, which number does violet stand for?
2. 2.🧩 Which component glows using little power? (a) LDR (b) motor (c) potentiometer (d) LED
3. 3.🔺 In the V-I-R triangle, how do we find V? (a) V = I ÷ R (b) V = I + R (c) V = R ÷ I (d) V = I × R
4. 4.🌈 A resistor has the colour bands brown, white, black. What is its value (in ohms)?
5. 5.True or false: the push of a cell is measured in watts (W). (a) False (b) True
6. 6.🧮 Two equal 470 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
7. 7.⚡ A device works on 3 V and takes 3 A. What is its power (in watts)? =
8. 8.🧾 A 60 W filament bulb is swapped for a 9 W LED lamp that gives about the same light. Both would run for 5 hours. How many watt-hours (Wh) are saved?
9. 9.🧩 Which component is a resistance knob? (a) potentiometer (b) capacitor (c) resistor (d) buzzer
10. 10.🧾 A 1500 W appliance runs for 8 hours. How many units (kWh) of electricity does it use? =
11. 11.🔺 A current of 1 A flows through a 12 Ω resistor. What is the voltage across it (in volts)? =
12. 12.🧩 Which component smooths a wobbly supply? (a) motor (b) resistor (c) LDR (d) capacitor
13. 13.🔺 A current of 40 mA flows through a 250 Ω resistor. What is the voltage across it (in volts)? =
14. 14.⚡ A 27 W device works on 9 V. What current does it take (in amperes)? =
15. 15.⚡ A device works on 6 V and takes 1.5 A. What is its power (in watts)? =
16. 16.🧮 A 33 Ω resistor is joined in series with two equal 330 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
17. 17.🧾 A 2000 W appliance runs for 8 hours. How many units (kWh) of electricity does it use? =
18. 18.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 3300 Ω resistor? (a) orange-orange-brown (b) orange-yellow-red (c) orange-orange-red (d) orange-orange-orange
19. 19.True or false: a resistor has coloured bands. (a) False (b) True
20. 20.🧮 A 3.6 V battery is joined to 6 Ω and 12 Ω resistors in series. What current flows (in amperes)? =
21. 21.🔺 A current of 1 A flows when 20 V is joined across a resistor. What is its resistance (in ohms)?
22. 22.True or false: the voltmeter measures voltage. (a) False (b) True
23. 23.🧾 A 60 W filament bulb is swapped for a 9 W LED lamp that gives about the same light. Both would run for 9 hours. How many watt-hours (Wh) are saved?
24. 24.🧮 Adding another resistor in series makes the total resistance … (a) zero (b) bigger (c) stay the same (d) smaller
25. 25.⚡ A 1.5 W device works on 3 V. What current does it take (in amperes)? =
26. 26.💡 What happens if an LED is put in backwards? (a) it makes a sound (b) it does not light (c) it changes colour (d) it lights brighter
27. 27.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 430 Ω resistor? (a) yellow-orange-brown (b) yellow-orange-red (c) yellow-orange-black (d) orange-yellow-brown
28. 28.True or false: a motor turns a fan or wheels. (a) True (b) False
29. 29.What does a thermistor do? (a) blows if current is high (b) boosts a small signal (c) beeps for an alarm (d) senses how hot it is
30. 30.🔍 Which is the odd one out? (a) leave fridge door open (b) close the fridge quickly (c) run fans in empty rooms (d) leave the TV on standby
31. 31.True or false: a capacitor smooths a wobbly supply. (a) True (b) False
32. 32.🔺 A current of 1.5 A flows through a 12 Ω resistor. What is the voltage across it (in volts)? =
33. 33.🔺 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
34. 34.🧩 Which part changes electrical energy into movement? (a) a motor (b) an LED (c) a fuse (d) a resistor
35. 35.True or false: the voltmeter measures current. (a) False (b) True
36. 36.🧮 A 3.25 V battery is joined to 8 Ω and 5 Ω resistors in series. What current flows (in amperes)? =
37. 37.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 26 Ω resistor? (a) blue-red-black (b) orange-blue-black (c) red-blue-brown (d) red-blue-black
38. 38.💡 An LED is joined to a 6 V battery with no 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
39. 39.🔺 A current of 25 mA flows through a 220 Ω resistor. What is the voltage across it (in volts)? =
40. 40.🧩 Which part changes electrical energy into sound? (a) a resistor (b) a capacitor (c) a diode (d) a buzzer

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