Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 847 · 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: to switch off empty rooms saves electricity. (a) False (b) True
2. 2.True or false: a motor beeps for an alarm. (a) False (b) True
3. 3.🧮 A 47 Ω resistor is joined in series with two equal 220 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
4. 4.🧩 Which component glows using little power? (a) motor (b) potentiometer (c) buzzer (d) LED
5. 5.⚡ A device works on 9 V and takes 1.5 A. What is its power (in watts)? =
6. 6.🔺 In the V-I-R triangle, how do we find I? (a) I = R ÷ V (b) I = V + R (c) I = V × R (d) I = V ÷ R
7. 7.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 1200 Ω resistor? (a) brown-red-red (b) red-brown-red (c) brown-red-orange (d) brown-red-brown
8. 8.🧮 Two equal 220 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
9. 9.🌈 A gold fourth band on a resistor means the value may be off by … (a) 50 % (b) 25 % (c) 0 % (d) 5 %
10. 10.⚡ A device works on 12 V and takes 1 A. What is its power (in watts)? =
11. 11.🧮 Two resistors in parallel give a total that is … (a) always zero (b) their sum (c) more than either one (d) less than either one
12. 12.💡 An LED is joined to a 12 V battery with no resistor; the leg next to the flat edge of its rim goes to the − side. What happens? (a) lights up (b) does not light (c) may burn out
13. 13.🧩 Which component makes a beeping sound? (a) buzzer (b) potentiometer (c) thermistor (d) motor
14. 14.💡 A red LED uses 2 V and should get 20 mA. It runs from a 12 V supply. What resistor (in ohms) is needed in series?
15. 15.📏 Voltmeter or ammeter: which one measures voltage? (a) ammeter (b) voltmeter
16. 16.🔺 A current of 0.5 A flows when 1.5 V is joined across a resistor. What is its resistance (in ohms)?
17. 17.🧩 Which component senses how hot it is? (a) resistor (b) capacitor (c) thermistor (d) buzzer
18. 18.🌈 In the resistor colour code, which number does brown stand for?
19. 19.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 55 Ω resistor? (a) green-green-brown (b) green-blue-black (c) green-green-black (d) blue-green-black
20. 20.🔺 A current of 20 mA flows through a 200 Ω resistor. What is the voltage across it (in volts)? =
21. 21.🧩 Which component senses how bright it is? (a) thermistor (b) diode (c) LDR (d) buzzer
22. 22.📏 How many amperes (A) is 1050 mA? =
23. 23.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 5100 Ω resistor? (a) green-brown-brown (b) green-brown-orange (c) brown-green-red (d) green-brown-red
24. 24.💡 What does LED stand for? (a) light energy dial (b) light-emitting diode (c) low energy device (d) large electric dial
25. 25.⚡ A 6 W device works on 3 V. What current does it take (in amperes)? =
26. 26.📏 How many ohms make 1 kilo-ohm (kΩ)? (a) 1024 (b) 1000 (c) 10 (d) 100
27. 27.🌈 In the resistor colour code, which number does grey stand for?
28. 28.⚡ A 1.2 W device works on 6 V. What current does it take (in amperes)? =
29. 29.🌈 A resistor has the colour bands white, brown, yellow. What is its value in kilo-ohms (kΩ)? =
30. 30.🔺 A current of 40 mA flows when 4 V is joined across a resistor. What is its resistance (in ohms)?
31. 31.🔍 Which is the odd one out? (a) leave the TV on standby (b) use old filament bulbs (c) use LED lamps (d) run fans in empty rooms
32. 32.🔺 A current of 10 mA flows through a 220 Ω resistor. What is the voltage across it (in volts)? =
33. 33.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 65000 Ω resistor? (a) green-blue-orange (b) blue-green-yellow (c) blue-green-orange (d) blue-green-red
34. 34.🧩 Which component lets current go one way? (a) buzzer (b) resistor (c) diode (d) capacitor
35. 35.🧮 A 68 Ω resistor is joined in series with two equal 20 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
36. 36.Which of these is measured in amperes (A)? (a) the flow of charge (b) voltage (c) how much a part resists (d) energy used each second
37. 37.💡 What happens if an LED is put in backwards? (a) it makes a sound (b) it lights brighter (c) it does not light (d) it changes colour
38. 38.⚡ A home appliance on the 230 V mains takes 2 A. What is its power (in watts)?
39. 39.Which of these is measured in watts (W)? (a) power (b) how much a part resists (c) voltage (d) resistance
40. 40.🌈 In the resistor colour code, which number does violet stand for?

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