Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 481 · 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.Which of these is measured in watts (W)? (a) how much a part resists (b) power (c) current (d) voltage
2. 2.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) gets bigger (b) gets smaller (c) becomes zero (d) stays the same
3. 3.🔺 A current of 1.5 A flows through a 6 Ω resistor. What is the voltage across it (in volts)? =
4. 4.🔺 A current of 0.5 A flows through a 4 Ω resistor. What is the voltage across it (in volts)? =
5. 5.💡 A blue LED uses 3 V and should get 20 mA. It runs from a 5 V supply. What resistor (in ohms) is needed in series?
6. 6.💡 An LED is joined to a 9 V battery through a 330 Ω resistor; its long leg goes to the + side and its short leg to the − side. What happens? (a) may burn out (b) lights up (c) does not light
7. 7.🧮 Adding another resistor in series makes the total resistance … (a) bigger (b) zero (c) stay the same (d) smaller
8. 8.🔺 A current of 2.5 A flows through a 2 Ω resistor. What is the voltage across it (in volts)? =
9. 9.🔺 A current of 1.5 A flows through a 5 Ω resistor. What is the voltage across it (in volts)? =
10. 10.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 39 Ω resistor? (a) yellow-white-black (b) orange-white-brown (c) orange-white-black (d) white-orange-black
11. 11.💡 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?
12. 12.📏 Voltmeter or ammeter: which one is joined across a part? (a) voltmeter (b) ammeter
13. 13.True or false: the ammeter measures current. (a) False (b) True
14. 14.🔺 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
15. 15.⚡ A home appliance on the 230 V mains takes 10 A. What is its power (in watts)?
16. 16.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 10 Ω resistor? (a) red-brown-black (b) brown-black-brown (c) red-black-black (d) brown-black-black
17. 17.⚡ Which formula gives electric power? (a) P = I ÷ V (b) P = V + I (c) P = V ÷ I (d) P = V × I
18. 18.🌈 A resistor has the colour bands grey, black, orange. What is its value in kilo-ohms (kΩ)? =
19. 19.🔺 A current of 20 mA flows through a 150 Ω resistor. What is the voltage across it (in volts)? =
20. 20.🧮 Four equal 80 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
21. 21.🔺 A current of 2 A flows through a 2 Ω resistor. What is the voltage across it (in volts)? =
22. 22.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark an 8500 Ω resistor? (a) grey-green-red (b) grey-green-orange (c) green-grey-red (d) grey-green-brown
23. 23.🔺 A current of 25 mA flows through a 400 Ω resistor. What is the voltage across it (in volts)? =
24. 24.Which of these saves electricity? (a) use old filament bulbs (b) run fans in empty rooms (c) use LED lamps (d) leave the TV on standby
25. 25.🧮 Two equal 200 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
26. 26.📏 How many amperes (A) is 610 mA? =
27. 27.📏 Which unit measures current? (a) ohm (Ω) (b) volt (V) (c) watt (W) (d) ampere (A)
28. 28.💡 What does LED stand for? (a) low energy device (b) light energy dial (c) large electric dial (d) light-emitting diode
29. 29.🔺 A 12.5 V supply is joined across a 250 Ω resistor. What current flows (in milliamperes, mA)?
30. 30.📏 In the water-pipe picture of a circuit, voltage is like … (a) the tap handle (b) the water pressure (c) the pipe colour (d) the water tank lid
31. 31.📏 Voltmeter or ammeter: which one measures voltage? (a) voltmeter (b) ammeter
32. 32.📏 Voltmeter or ammeter: which one is joined in series? (a) voltmeter (b) ammeter
33. 33.🔺 A current of 50 mA flows when 7.5 V is joined across a resistor. What is its resistance (in ohms)?
34. 34.🧾 One “unit” on an electricity bill is … (a) 1 kilowatt-hour (kWh) (b) 1 watt (c) 1 volt (d) 1 ampere
35. 35.📏 Which unit measures the push of a cell? (a) ohm (Ω) (b) watt (W) (c) ampere (A) (d) volt (V)
36. 36.🧩 Which component has coloured bands? (a) LDR (b) diode (c) resistor (d) potentiometer
37. 37.📏 How many milliamperes (mA) is 1.22 A?
38. 38.🔺 A current of 1 A flows through a 2 Ω resistor. What is the voltage across it (in volts)? =
39. 39.🧮 Two equal 20 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
40. 40.🌈 Which band is read first on a resistor? (a) the gold band (b) the one nearest an end (c) any band (d) the widest gap

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