Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 299 · 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.True or false: a buzzer makes a beeping sound. (a) True (b) False
2. 2.What does a potentiometer do? (a) beeps for an alarm (b) limits the current (c) is a resistance knob (d) turns a fan or wheels
3. 3.⚡ A home appliance on the 230 V mains takes 4 A. What is its power (in watts)?
4. 4.🌈 A gold fourth band on a resistor means the value may be off by … (a) 50 % (b) 25 % (c) 5 % (d) 0 %
5. 5.💡 An LED is joined to a 12 V battery with no 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
6. 6.🔺 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
7. 7.💡 What does LED stand for? (a) light-emitting diode (b) large electric dial (c) light energy dial (d) low energy device
8. 8.💡 On an LED, is the shorter leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
9. 9.⚡ A 4.5 W device works on 1.5 V. What current does it take (in amperes)? =
10. 10.Which of these wastes electricity? (a) leave fridge door open (b) set the AC to 24 °C (c) unplug idle chargers (d) use LED lamps
11. 11.⚡ A device works on 3 V and takes 0.1 A. What is its power (in watts)? =
12. 12.📏 How many milliamperes (mA) make 1 ampere? (a) 10 (b) 60 (c) 1000 (d) 100
13. 13.🧮 Adding another resistor in series makes the total resistance … (a) stay the same (b) zero (c) bigger (d) smaller
14. 14.🔺 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
15. 15.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 20000 Ω resistor? (a) red-black-red (b) red-black-yellow (c) orange-red-orange (d) red-black-orange
16. 16.🔺 A current of 0.5 A flows when 7.5 V is joined across a resistor. What is its resistance (in ohms)?
17. 17.True or false: on an LED, the shorter leg is the cathode (−). (a) False (b) True
18. 18.🧮 Resistors of 330 Ω and 22 Ω are joined in series. What is the total resistance (in ohms)?
19. 19.📏 In the water-pipe picture of a circuit, resistance is like … (a) a bigger tank (b) the flow of water (c) the water pressure (d) a narrow pipe
20. 20.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 9700 Ω resistor? (a) white-violet-brown (b) white-violet-orange (c) violet-white-red (d) white-violet-red
21. 21.⚡ A 0.75 W device works on 3 V. What current does it take (in amperes)? =
22. 22.📏 Voltmeter or ammeter: which one is joined in series? (a) voltmeter (b) ammeter
23. 23.Which of these is measured in ohms (Ω)? (a) voltage (b) resistance (c) power (d) the push of a cell
24. 24.🔺 A current of 25 mA flows through a 250 Ω resistor. What is the voltage across it (in volts)? =
25. 25.🔺 A current of 0.1 A flows through an 8 Ω resistor. What is the voltage across it (in volts)? =
26. 26.🔺 A current of 10 mA flows through a 100 Ω resistor. What is the voltage across it (in volts)? =
27. 27.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) gets smaller (b) becomes zero (c) gets bigger (d) stays the same
28. 28.📏 How many watts (W) is 0.4 kW?
29. 29.🌈 A resistor has the colour bands yellow, blue, red. What is its value in kilo-ohms (kΩ)? =
30. 30.🌈 A resistor has the colour bands grey, orange, black. What is its value (in ohms)?
31. 31.True or false: a fuse turns a fan or wheels. (a) True (b) False
32. 32.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 27 Ω resistor? (a) red-violet-black (b) violet-red-black (c) orange-violet-black (d) red-violet-brown
33. 33.⚡ A 0.3 W device works on 3 V. What current does it take (in amperes)? =
34. 34.True or false: a buzzer makes things spin. (a) True (b) False
35. 35.⚡ Power tells us … (a) the length of a wire (b) energy used each second (c) the size of a cell (d) the colour of light
36. 36.📏 Voltmeter or ammeter: which one measures voltage? (a) voltmeter (b) ammeter
37. 37.💡 Why does an LED need a resistor in series? (a) to change its colour (b) to make it brighter (c) to limit the current (d) to store charge
38. 38.📏 How many kilowatts (kW) is 1350 W? =
39. 39.💡 On an LED, is the leg by the flat edge the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
40. 40.🔺 A current of 25 mA flows when 11.75 V is joined across a resistor. What is its resistance (in ohms)?

Free electronics lessons, practice and worksheets at talentjr.in/electronics-for-kids