Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 35 · 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) energy used each second (b) the flow of charge (c) current (d) how much a part resists
2. 2.🔺 A current of 20 mA flows through a 100 Ω resistor. What is the voltage across it (in volts)? =
3. 3.🌈 In the resistor colour code, which number does blue stand for?
4. 4.💡 What does LED stand for? (a) low energy device (b) light-emitting diode (c) large electric dial (d) light energy dial
5. 5.🔺 A current of 10 mA flows through a 470 Ω resistor. What is the voltage across it (in volts)? =
6. 6.🌈 A resistor has the colour bands violet, yellow, red. What is its value (in ohms)?
7. 7.🔺 A current of 0.2 A flows through a 6 Ω resistor. What is the voltage across it (in volts)? =
8. 8.Which of these is measured in volts (V)? (a) resistance (b) power (c) the push of a cell (d) current
9. 9.📏 Which unit measures how much a part resists? (a) watt (W) (b) volt (V) (c) ampere (A) (d) ohm (Ω)
10. 10.📏 In the water-pipe picture of a circuit, voltage is like … (a) the pipe colour (b) the water tank lid (c) the tap handle (d) the water pressure
11. 11.🔺 In the V-I-R triangle, how do we find V? (a) V = I ÷ R (b) V = R ÷ I (c) V = I × R (d) V = I + R
12. 12.🔺 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
13. 13.📏 Which unit measures energy used each second? (a) ohm (Ω) (b) volt (V) (c) watt (W) (d) ampere (A)
14. 14.⚡ A device works on 1.5 V and takes 3 A. What is its power (in watts)? =
15. 15.🔺 A current of 0.5 A flows when 6 V is joined across a resistor. What is its resistance (in ohms)?
16. 16.📏 In the water-pipe picture of a circuit, resistance is like … (a) the water pressure (b) the flow of water (c) a narrow pipe (d) a bigger tank
17. 17.📏 How many amperes (A) is 270 mA? =
18. 18.⚡ A home appliance on the 230 V mains takes 0.5 A. What is its power (in watts)?
19. 19.⚡ A device works on 9 V and takes 1 A. What is its power (in watts)? =
20. 20.🧮 A 20 Ω resistor is joined in series with two equal 100 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
21. 21.⚡ Power tells us … (a) the colour of light (b) the length of a wire (c) the size of a cell (d) energy used each second
22. 22.💡 A red LED (it uses 2 V) is joined with a 300 Ω resistor to a 6.5 V supply. What current flows (in mA)?
23. 23.🔺 A 0.5 V supply is joined across a 5 Ω resistor. What current flows (in amperes)? =
24. 24.📏 How many milliamperes (mA) is 0.8 A?
25. 25.🧮 Adding another resistor in series makes the total resistance … (a) bigger (b) zero (c) smaller (d) stay the same
26. 26.True or false: to use daylight to read saves electricity. (a) False (b) True
27. 27.📏 Which unit measures current? (a) volt (V) (b) ampere (A) (c) ohm (Ω) (d) watt (W)
28. 28.💡 On an LED, is the longer leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
29. 29.🧮 Two resistors in parallel give a total that is … (a) less than either one (b) more than either one (c) their sum (d) always zero
30. 30.🧮 Resistors of 220 Ω and 20 Ω are joined in series. What is the total resistance (in ohms)?
31. 31.🧩 Which component beeps for an alarm? (a) buzzer (b) capacitor (c) LDR (d) fuse
32. 32.🔺 A 10 V supply is joined across a 500 Ω resistor. What current flows (in milliamperes, mA)?
33. 33.🌈 A resistor has the colour bands red, red, red. What is its value in kilo-ohms (kΩ)? =
34. 34.💡 A red LED uses 2 V and should get 10 mA. It runs from a 6 V supply. What resistor (in ohms) is needed in series?
35. 35.🌈 A resistor has the colour bands yellow, white, red. What is its value in kilo-ohms (kΩ)? =
36. 36.🧩 Which part changes electrical energy into sound? (a) a capacitor (b) a buzzer (c) a diode (d) a resistor
37. 37.📏 How many milliamperes (mA) is 1.59 A?
38. 38.What does a thermistor do? (a) senses how hot it is (b) smooths a wobbly supply (c) glows using little power (d) beeps for an alarm
39. 39.🔺 A current of 25 mA flows through a 330 Ω resistor. What is the voltage across it (in volts)? =
40. 40.📏 Voltmeter or ammeter: which one measures voltage? (a) ammeter (b) voltmeter

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