Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 712 · 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.💡 Does it save or waste electricity to use old filament bulbs? (a) saves electricity (b) wastes electricity
2. 2.💡 What does LED stand for? (a) light-emitting diode (b) low energy device (c) light energy dial (d) large electric dial
3. 3.🧮 A 150 Ω resistor is joined in series with two equal 470 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
4. 4.🧮 Resistors of 68 Ω and 10 Ω are joined in series. What is the total resistance (in ohms)?
5. 5.⚡ A device works on 6 V and takes 1 A. What is its power (in watts)? =
6. 6.💡 On an LED, is the leg by the flat edge the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
7. 7.💡 A blue LED uses 3 V and should get 20 mA. It runs from a 6 V supply. What resistor (in ohms) is needed in series?
8. 8.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) gets smaller (b) becomes zero (c) stays the same (d) gets bigger
9. 9.📏 How many kilo-ohms (kΩ) is 4500 Ω? =
10. 10.🔺 A current of 1.5 A flows through a 5 Ω resistor. What is the voltage across it (in volts)? =
11. 11.🔺 A current of 40 mA flows when 18.8 V is joined across a resistor. What is its resistance (in ohms)?
12. 12.💡 On an LED, is the longer leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
13. 13.What does a capacitor do? (a) beeps for an alarm (b) lets current go one way (c) turns a fan or wheels (d) stores a little charge
14. 14.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 6300 Ω resistor? (a) blue-orange-red (b) orange-blue-red (c) blue-orange-orange (d) blue-orange-brown
15. 15.🔍 Which is the odd one out? (a) use LED lamps (b) iron one shirt at a time (c) use old filament bulbs (d) leave fridge door open
16. 16.⚡ A device works on 12 V and takes 3 A. What is its power (in watts)? =
17. 17.🔺 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
18. 18.🔺 A current of 1.5 A flows through a 20 Ω resistor. What is the voltage across it (in volts)? =
19. 19.⚡ A home appliance on the 230 V mains takes 0.5 A. What is its power (in watts)?
20. 20.⚡ Which formula gives electric power? (a) P = V ÷ I (b) P = V + I (c) P = I ÷ V (d) P = V × I
21. 21.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark an 830 Ω resistor? (a) grey-orange-black (b) orange-grey-brown (c) grey-orange-brown (d) grey-orange-red
22. 22.💡 An LED is joined to a 3 V battery through a 330 Ω resistor; the leg next to the flat edge of its rim goes to the + side. What happens? (a) lights up (b) may burn out (c) does not light
23. 23.🌈 In the resistor colour code, which number does black stand for?
24. 24.True or false: a potentiometer is a resistance knob. (a) True (b) False
25. 25.🔺 A current of 0.1 A flows through a 3 Ω resistor. What is the voltage across it (in volts)? =
26. 26.🧮 Three equal 60 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
27. 27.🧮 Two equal 200 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
28. 28.🔺 A 10 V supply is joined across a 20 Ω resistor. What current flows (in amperes)? =
29. 29.🔺 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
30. 30.True or false: on an LED, the round-side leg is the cathode (−). (a) False (b) True
31. 31.⚡ A device works on 24 V and takes 3 A. What is its power (in watts)? =
32. 32.🧮 A 330 Ω resistor is joined in series with two equal 40 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
33. 33.🔺 A 0.4 V supply is joined across a 4 Ω resistor. What current flows (in amperes)? =
34. 34.True or false: the ammeter measures voltage. (a) True (b) False
35. 35.🔺 A current of 0.5 A flows through a 20 Ω resistor. What is the voltage across it (in volts)? =
36. 36.🌈 Which band is read first on a resistor? (a) any band (b) the widest gap (c) the gold band (d) the one nearest an end
37. 37.🌈 A resistor has the colour bands blue, red, orange. What is its value (in ohms)?
38. 38.📏 Voltmeter or ammeter: which one is joined in series? (a) voltmeter (b) ammeter
39. 39.🔺 A 23.5 V supply is joined across a 470 Ω resistor. What current flows (in milliamperes, mA)?
40. 40.💡 A red LED uses 2 V and should get 25 mA. It runs from a 6 V supply. What resistor (in ohms) is needed in series?

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