Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 713 · 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 0.15 W device works on 1.5 V. What current does it take (in amperes)? =
2. 2.📏 Voltmeter or ammeter: which one is joined across a part? (a) ammeter (b) voltmeter
3. 3.⚡ A 6 W device works on 3 V. What current does it take (in amperes)? =
4. 4.🧮 Resistors of 22 Ω, 50 Ω, 150 Ω and 220 Ω are joined in series. What is the total resistance (in ohms)?
5. 5.📏 Which unit measures energy used each second? (a) ampere (A) (b) ohm (Ω) (c) volt (V) (d) watt (W)
6. 6.🔺 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
7. 7.Which of these is measured in ohms (Ω)? (a) resistance (b) voltage (c) power (d) the push of a cell
8. 8.🔺 A current of 1.5 A flows through a 2 Ω resistor. What is the voltage across it (in volts)? =
9. 9.⚡ Power tells us … (a) energy used each second (b) the length of a wire (c) the colour of light (d) the size of a cell
10. 10.True or false: to use daylight to read saves electricity. (a) False (b) True
11. 11.⚡ A home appliance on the 230 V mains takes 5 A. What is its power (in watts)?
12. 12.💡 Why does an LED need a resistor in series? (a) to make it brighter (b) to change its colour (c) to store charge (d) to limit the current
13. 13.📏 How many milliamperes (mA) is 0.97 A?
14. 14.🔍 Which is the odd one out? (a) unplug idle chargers (b) set the AC to 24 °C (c) leave fridge door open (d) use daylight to read
15. 15.💡 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) does not light (b) lights up (c) may burn out
16. 16.⚡ Which formula gives electric power? (a) P = V + I (b) P = V ÷ I (c) P = I ÷ V (d) P = V × I
17. 17.🔺 A current of 2.5 A flows through a 4 Ω resistor. What is the voltage across it (in volts)? =
18. 18.📏 In the water-pipe picture of a circuit, resistance is like … (a) the water pressure (b) a narrow pipe (c) a bigger tank (d) the flow of water
19. 19.🧩 Which component blows if current is high? (a) fuse (b) LDR (c) LED (d) potentiometer
20. 20.🔺 A current of 40 mA flows when 18.8 V is joined across a resistor. What is its resistance (in ohms)?
21. 21.True or false: a resistor stores a little charge. (a) False (b) True
22. 22.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 76000 Ω resistor? (a) violet-blue-orange (b) violet-blue-red (c) violet-blue-yellow (d) blue-violet-orange
23. 23.🔺 A current of 40 mA flows through a 500 Ω resistor. What is the voltage across it (in volts)? =
24. 24.💡 Does it save or waste electricity to use daylight to read? (a) saves electricity (b) wastes electricity
25. 25.📏 How many amperes (A) is 410 mA? =
26. 26.🌈 A resistor has the colour bands violet, green, orange. What is its value in kilo-ohms (kΩ)? =
27. 27.💡 An LED is joined to a 9 V battery through a 470 Ω resistor; its long leg goes to the − side and its short leg to the + side. What happens? (a) does not light (b) lights up (c) may burn out
28. 28.Which of these is measured in watts (W)? (a) power (b) how much a part resists (c) voltage (d) the flow of charge
29. 29.💡 An LED is joined to a 5 V battery with no resistor; the leg next to the flat edge of its rim goes to the − side. What happens? (a) does not light (b) may burn out (c) lights up
30. 30.💡 Does it save or waste electricity to switch off empty rooms? (a) wastes electricity (b) saves electricity
31. 31.True or false: how much a part resists is measured in watts (W). (a) True (b) False
32. 32.💡 A red LED (it uses 2 V) is joined with a 100 Ω resistor to a 4 V supply. What current flows (in mA)?
33. 33.True or false: a transistor smooths a wobbly supply. (a) True (b) False
34. 34.🌈 Which band is read first on a resistor? (a) the one nearest an end (b) the widest gap (c) the gold band (d) any band
35. 35.🧮 Resistors of 150 Ω, 20 Ω, 50 Ω and 47 Ω are joined in series. What is the total resistance (in ohms)?
36. 36.⚡ A 1.5 W device works on 6 V. What current does it take (in amperes)? =
37. 37.🧩 Which component stores a little charge? (a) capacitor (b) diode (c) buzzer (d) fuse
38. 38.💡 On an LED, is the leg by the flat edge the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
39. 39.🔺 A current of 3 A flows when 9 V is joined across a resistor. What is its resistance (in ohms)?
40. 40.📏 How many amperes (A) is 2830 mA? =

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