Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 445 · 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.⚡ A 6 W device works on 3 V. What current does it take (in amperes)? =
2. 2.What does an LDR do? (a) lets current go one way (b) senses how bright it is (c) boosts a small signal (d) stores a little charge
3. 3.True or false: to leave the TV on standby saves electricity. (a) False (b) True
4. 4.🔺 A 1 V supply is joined across a 10 Ω resistor. What current flows (in amperes)? =
5. 5.⚡ Power tells us … (a) the size of a cell (b) the length of a wire (c) energy used each second (d) the colour of light
6. 6.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) gets bigger (b) becomes zero (c) gets smaller (d) stays the same
7. 7.🔺 A current of 3 A flows through a 20 Ω resistor. What is the voltage across it (in volts)? =
8. 8.🧮 Resistors of 33 Ω and 68 Ω are joined in series. What is the total resistance (in ohms)?
9. 9.🔺 A current of 10 mA flows when 1.5 V is joined across a resistor. What is its resistance (in ohms)?
10. 10.⚡ A 0.9 W device works on 9 V. What current does it take (in amperes)? =
11. 11.🔺 A current of 40 mA flows when 8.8 V is joined across a resistor. What is its resistance (in ohms)?
12. 12.What does a buzzer do? (a) beeps for an alarm (b) limits the current (c) blows if current is high (d) turns a fan or wheels
13. 13.🌈 In the resistor colour code, which number does orange stand for?
14. 14.⚡ A device works on 24 V and takes 0.1 A. What is its power (in watts)? =
15. 15.Which of these is measured in volts (V)? (a) how much a part resists (b) current (c) the push of a cell (d) the flow of charge
16. 16.💡 An LED is joined to a 5 V battery through a 1000 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
17. 17.🧮 Two resistors in parallel give a total that is … (a) less than either one (b) their sum (c) more than either one (d) always zero
18. 18.🌈 A resistor has the colour bands orange, brown, black. What is its value (in ohms)?
19. 19.True or false: to iron one shirt at a time wastes electricity. (a) True (b) False
20. 20.📏 Voltmeter or ammeter: which one measures voltage? (a) ammeter (b) voltmeter
21. 21.True or false: a buzzer beeps for an alarm. (a) True (b) False
22. 22.What does a diode do? (a) makes things spin (b) lets current go one way (c) senses how hot it is (d) turns a fan or wheels
23. 23.🌈 A gold fourth band on a resistor means the value may be off by … (a) 50 % (b) 0 % (c) 5 % (d) 25 %
24. 24.📏 How many watts (W) is 0.8 kW?
25. 25.🔍 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
26. 26.📏 How many milliamperes (mA) make 1 ampere? (a) 60 (b) 100 (c) 1000 (d) 10
27. 27.📏 Which unit measures the push of a cell? (a) ampere (A) (b) volt (V) (c) watt (W) (d) ohm (Ω)
28. 28.🔺 A current of 50 mA flows through a 150 Ω resistor. What is the voltage across it (in volts)? =
29. 29.💡 A red LED (it uses 2 V) is joined with a 300 Ω resistor to a 5 V supply. What current flows (in mA)?
30. 30.🧮 Resistors of 10 Ω and 33 Ω are joined in series. What is the total resistance (in ohms)?
31. 31.🔺 A 20 V supply is joined across a 20 Ω resistor. What current flows (in amperes)? =
32. 32.📏 How many ohms (Ω) is 2 kΩ?
33. 33.🌈 A resistor has the colour bands grey, violet, yellow. What is its value in kilo-ohms (kΩ)? =
34. 34.🔺 A current of 50 mA flows through a 100 Ω resistor. What is the voltage across it (in volts)? =
35. 35.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark an 800 Ω resistor? (a) grey-black-red (b) grey-black-brown (c) white-grey-brown (d) grey-black-black
36. 36.⚡ A 1.8 W device works on 9 V. What current does it take (in amperes)? =
37. 37.🌈 In the resistor colour code, which number does green stand for?
38. 38.🔺 A 15 V supply is joined across a 5 Ω resistor. What current flows (in amperes)? =
39. 39.Which of these is measured in volts (V)? (a) resistance (b) how much a part resists (c) current (d) voltage
40. 40.What does a transistor do? (a) boosts a small signal (b) stores a little charge (c) smooths a wobbly supply (d) has coloured bands

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