Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 767 · 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 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
2. 2.🧮 A 16 V battery is joined to 4 Ω and 12 Ω resistors in series. What current flows (in amperes)? =
3. 3.🌈 A gold fourth band on a resistor means the value may be off by … (a) 0 % (b) 5 % (c) 50 % (d) 25 %
4. 4.⚡ Which formula gives electric power? (a) P = V + I (b) P = V ÷ I (c) P = V × I (d) P = I ÷ V
5. 5.📏 In the water-pipe picture of a circuit, current is like … (a) the pipe colour (b) the water pressure (c) the flow of water (d) a narrow pipe
6. 6.⚡ A 48 W device works on 24 V. What current does it take (in amperes)? =
7. 7.⚡ A 3 W device works on 1.5 V. What current does it take (in amperes)? =
8. 8.🔺 A current of 2.5 A flows through a 2 Ω resistor. What is the voltage across it (in volts)? =
9. 9.💡 On an LED, is the longer leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
10. 10.📏 How many milliamperes (mA) is 1.35 A?
11. 11.True or false: to use LED lamps saves electricity. (a) False (b) True
12. 12.🌈 In the resistor colour code, which number does red stand for?
13. 13.🌈 A resistor has the colour bands red, grey, black. What is its value (in ohms)?
14. 14.🌈 A resistor has the colour bands grey, violet, red. What is its value (in ohms)?
15. 15.True or false: power is measured in amperes (A). (a) True (b) False
16. 16.🔺 A current of 0.2 A flows when 0.6 V is joined across a resistor. What is its resistance (in ohms)?
17. 17.What does a buzzer do? (a) glows using little power (b) makes a beeping sound (c) senses how bright it is (d) lets current go one way
18. 18.🔺 A current of 1.5 A flows through a 3 Ω resistor. What is the voltage across it (in volts)? =
19. 19.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) becomes zero (b) gets smaller (c) stays the same (d) gets bigger
20. 20.🧾 One “unit” on an electricity bill is … (a) 1 watt (b) 1 volt (c) 1 ampere (d) 1 kilowatt-hour (kWh)
21. 21.🔍 Which is the odd one out? (a) use LED lamps (b) use old filament bulbs (c) close the fridge quickly (d) switch off empty rooms
22. 22.🌈 In the resistor colour code, which number does green stand for?
23. 23.⚡ A home appliance on the 230 V mains takes 5 A. What is its power (in watts)?
24. 24.🔺 A current of 0.25 A flows through a 5 Ω resistor. What is the voltage across it (in volts)? =
25. 25.⚡ A home appliance on the 230 V mains takes 8 A. What is its power (in watts)?
26. 26.🔺 A current of 3 A flows through a 15 Ω resistor. What is the voltage across it (in volts)? =
27. 27.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 930 Ω resistor? (a) white-orange-brown (b) white-orange-red (c) white-orange-black (d) orange-white-brown
28. 28.🧮 A 470 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)?
29. 29.🔺 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
30. 30.⚡ A device works on 1.5 V and takes 0.25 A. What is its power (in watts)? =
31. 31.🌈 Which band is read first on a resistor? (a) the widest gap (b) the one nearest an end (c) the gold band (d) any band
32. 32.True or false: a buzzer makes a beeping sound. (a) True (b) False
33. 33.🧮 Two equal 100 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
34. 34.⚡ A home appliance on the 230 V mains takes 10 A. What is its power (in watts)?
35. 35.True or false: resistance is measured in ohms (Ω). (a) True (b) False
36. 36.💡 Does it save or waste electricity to run fans in empty rooms? (a) saves electricity (b) wastes electricity
37. 37.🔺 A current of 2.5 A flows through a 4 Ω resistor. What is the voltage across it (in volts)? =
38. 38.⚡ A home appliance on the 230 V mains takes 1.5 A. What is its power (in watts)?
39. 39.🌈 A resistor has the colour bands grey, blue, yellow. What is its value in kilo-ohms (kΩ)? =
40. 40.True or false: an LDR has coloured bands. (a) True (b) False

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