Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 501 · 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.Which of these saves electricity? (a) unplug idle chargers (b) leave the TV on standby (c) use old filament bulbs (d) iron one shirt at a time
2. 2.🔺 A current of 0.2 A flows through a 2 Ω resistor. What is the voltage across it (in volts)? =
3. 3.🧮 A 2.2 V battery is joined to 12 Ω and 10 Ω resistors in series. What current flows (in amperes)? =
4. 4.📏 Which unit measures power? (a) ohm (Ω) (b) volt (V) (c) watt (W) (d) ampere (A)
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.🔺 A current of 10 mA flows when 5 V is joined across a resistor. What is its resistance (in ohms)?
7. 7.Which of these wastes electricity? (a) unplug idle chargers (b) leave the TV on standby (c) set the AC to 24 °C (d) use LED lamps
8. 8.⚡ A home appliance on the 230 V mains takes 10 A. What is its power (in watts)?
9. 9.🔺 A current of 25 mA flows through a 200 Ω resistor. What is the voltage across it (in volts)? =
10. 10.🔺 A current of 1 A flows when 12 V is joined across a resistor. What is its resistance (in ohms)?
11. 11.🌈 A resistor has the colour bands grey, yellow, red. What is its value in kilo-ohms (kΩ)? =
12. 12.💡 A blue LED uses 3 V and should get 10 mA. It runs from a 5 V supply. What resistor (in ohms) is needed in series?
13. 13.📏 Which unit measures current? (a) volt (V) (b) ampere (A) (c) watt (W) (d) ohm (Ω)
14. 14.📏 Which unit measures voltage? (a) ohm (Ω) (b) watt (W) (c) volt (V) (d) ampere (A)
15. 15.⚡ A device works on 12 V and takes 1.5 A. What is its power (in watts)? =
16. 16.🌈 A resistor has the colour bands brown, red, brown. What is its value (in ohms)?
17. 17.📏 In the water-pipe picture of a circuit, resistance is like … (a) a bigger tank (b) the water pressure (c) a narrow pipe (d) the flow of water
18. 18.What does a potentiometer do? (a) glows using little power (b) is a resistance knob (c) beeps for an alarm (d) lets current go one way
19. 19.⚡ A 1.8 W device works on 9 V. What current does it take (in amperes)? =
20. 20.🌈 A resistor has the colour bands red, yellow, red. What is its value (in ohms)?
21. 21.📏 How many ohms make 1 kilo-ohm (kΩ)? (a) 10 (b) 1000 (c) 100 (d) 1024
22. 22.🌈 In the resistor colour code, which number does red stand for?
23. 23.🧾 A 250 W appliance runs for 2 hours. How many units (kWh) of electricity does it use? =
24. 24.True or false: to use old filament bulbs saves electricity. (a) True (b) False
25. 25.🌈 A resistor has the colour bands violet, black, red. What is its value in kilo-ohms (kΩ)? =
26. 26.🧮 Four equal 20 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
27. 27.True or false: the voltmeter is joined across a part. (a) True (b) False
28. 28.🧮 A 2 V battery is joined to 6 Ω and 4 Ω resistors in series. What current flows (in amperes)? =
29. 29.🔺 A current of 40 mA flows through a 330 Ω resistor. What is the voltage across it (in volts)? =
30. 30.What does an LDR do? (a) turns a fan or wheels (b) has coloured bands (c) senses how bright it is (d) is a resistance knob
31. 31.What does an LED do? (a) makes a beeping sound (b) glows using little power (c) senses how hot it is (d) stores a little charge
32. 32.🔺 A 10 V supply is joined across a 4 Ω resistor. What current flows (in amperes)? =
33. 33.🔺 In the V-I-R triangle, how do we find V? (a) V = R ÷ I (b) V = I ÷ R (c) V = I + R (d) V = I × R
34. 34.💡 What happens if an LED is put in backwards? (a) it makes a sound (b) it changes colour (c) it lights brighter (d) it does not light
35. 35.📏 Which unit measures how much a part resists? (a) ampere (A) (b) volt (V) (c) ohm (Ω) (d) watt (W)
36. 36.🌈 In the resistor colour code, which number does yellow stand for?
37. 37.🌈 A resistor has the colour bands yellow, grey, orange. What is its value (in ohms)?
38. 38.🔺 A current of 0.2 A flows when 2 V is joined across a resistor. What is its resistance (in ohms)?
39. 39.🧮 Adding another resistor in series makes the total resistance … (a) smaller (b) zero (c) stay the same (d) bigger
40. 40.🧩 Which part changes electrical energy into sound? (a) a buzzer (b) a resistor (c) a capacitor (d) a diode

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