Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 48 · 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 R? (a) R = I ÷ V (b) R = V + I (c) R = V ÷ I (d) R = V × I
2. 2.🔺 A current of 25 mA flows when 5.5 V is joined across a resistor. What is its resistance (in ohms)?
3. 3.⚡ A 0.6 W device works on 3 V. What current does it take (in amperes)? =
4. 4.⚡ A 12 W device works on 12 V. What current does it take (in amperes)? =
5. 5.⚡ A device works on 6 V and takes 0.1 A. What is its power (in watts)? =
6. 6.🌈 In the resistor colour code, which number does brown stand for?
7. 7.🌈 A gold fourth band on a resistor means the value may be off by … (a) 5 % (b) 25 % (c) 50 % (d) 0 %
8. 8.💡 Why does an LED need a resistor in series? (a) to change its colour (b) to store charge (c) to make it brighter (d) to limit the current
9. 9.🔺 A current of 50 mA flows through a 100 Ω resistor. What is the voltage across it (in volts)? =
10. 10.💡 Does it save or waste electricity to iron one shirt at a time? (a) wastes electricity (b) saves electricity
11. 11.🧮 Two equal 40 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
12. 12.🔺 A current of 25 mA flows through a 220 Ω resistor. What is the voltage across it (in volts)? =
13. 13.🔺 A current of 0.5 A flows when 1.5 V is joined across a resistor. What is its resistance (in ohms)?
14. 14.🔺 A current of 50 mA flows through a 250 Ω resistor. What is the voltage across it (in volts)? =
15. 15.🔺 In the V-I-R triangle, how do we find I? (a) I = V ÷ R (b) I = V + R (c) I = R ÷ V (d) I = V × R
16. 16.🔺 A current of 2 A flows through an 8 Ω resistor. What is the voltage across it (in volts)? =
17. 17.🔺 A current of 0.25 A flows through an 8 Ω resistor. What is the voltage across it (in volts)? =
18. 18.🌈 A resistor has the colour bands white, red, red. What is its value in kilo-ohms (kΩ)? =
19. 19.🔺 A current of 20 mA flows when 5 V is joined across a resistor. What is its resistance (in ohms)?
20. 20.What does a diode do? (a) lets current go one way (b) senses how hot it is (c) senses how bright it is (d) beeps for an alarm
21. 21.🔺 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
22. 22.🧮 A 2.75 V battery is joined to 6 Ω and 5 Ω resistors in series. What current flows (in amperes)? =
23. 23.🔺 A current of 2.5 A flows when 10 V is joined across a resistor. What is its resistance (in ohms)?
24. 24.🌈 A resistor has the colour bands brown, green, black. What is its value (in ohms)?
25. 25.💡 What does LED stand for? (a) low energy device (b) light energy dial (c) light-emitting diode (d) large electric dial
26. 26.🔺 A current of 10 mA flows through a 300 Ω resistor. What is the voltage across it (in volts)? =
27. 27.💡 An LED is joined to a 3 V battery through a 330 Ω resistor; its long leg goes to the + side and its short leg to the − side. What happens? (a) lights up (b) may burn out (c) does not light
28. 28.💡 Does it save or waste electricity to use LED lamps? (a) wastes electricity (b) saves electricity
29. 29.📏 How many kilo-ohms (kΩ) is 6700 Ω? =
30. 30.💡 A red LED (it uses 2 V) is joined with a 150 Ω resistor to a 4.25 V supply. What current flows (in mA)?
31. 31.True or false: the push of a cell is measured in watts (W). (a) False (b) True
32. 32.🧮 Four equal 200 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
33. 33.⚡ A device works on 3 V and takes 1 A. What is its power (in watts)? =
34. 34.🧮 A 220 Ω resistor is joined in series with two equal 200 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
35. 35.True or false: a fuse smooths a wobbly supply. (a) False (b) True
36. 36.📏 How many watts (W) is 4.9 kW?
37. 37.🧮 Two resistors in parallel give a total that is … (a) their sum (b) always zero (c) more than either one (d) less than either one
38. 38.⚡ A device works on 24 V and takes 0.5 A. What is its power (in watts)? =
39. 39.True or false: the voltmeter is joined in series. (a) False (b) True
40. 40.💡 A red LED (it uses 2 V) is joined with a 300 Ω resistor to a 5 V supply. What current flows (in mA)?

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