Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 599 · 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 0.3 V supply is joined across a 3 Ω resistor. What current flows (in amperes)? =
2. 2.True or false: the ammeter measures current. (a) False (b) True
3. 3.💡 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
4. 4.True or false: on an LED, the round-side leg is the cathode (−). (a) True (b) False
5. 5.🔺 A current of 0.25 A flows when 1.25 V is joined across a resistor. What is its resistance (in ohms)?
6. 6.🌈 A gold fourth band on a resistor means the value may be off by … (a) 0 % (b) 5 % (c) 25 % (d) 50 %
7. 7.🔺 A 1.2 V supply is joined across a 6 Ω resistor. What current flows (in amperes)? =
8. 8.🧮 A 3.6 V battery is joined to 12 Ω and 6 Ω resistors in series. What current flows (in amperes)? =
9. 9.🔺 An 8.8 V supply is joined across a 220 Ω resistor. What current flows (in milliamperes, mA)?
10. 10.📏 Voltmeter or ammeter: which one measures voltage? (a) voltmeter (b) ammeter
11. 11.💡 On an LED, is the shorter leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
12. 12.🧩 A capacitor in a circuit can … (a) measure heat (b) make light (c) spin a wheel (d) store charge briefly
13. 13.🧩 Which component senses how hot it is? (a) thermistor (b) capacitor (c) fuse (d) potentiometer
14. 14.⚡ A 0.3 W device works on 1.5 V. What current does it take (in amperes)? =
15. 15.💡 On an LED, is the round-side leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
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 6 V supply is joined across a 6 Ω resistor. What current flows (in amperes)? =
18. 18.🧮 Two resistors in parallel give a total that is … (a) their sum (b) always zero (c) more than either one (d) less than either one
19. 19.🔺 A 2.5 V supply is joined across a 5 Ω resistor. What current flows (in amperes)? =
20. 20.🧮 Adding another resistor in series makes the total resistance … (a) zero (b) smaller (c) stay the same (d) bigger
21. 21.🔺 A current of 10 mA flows when 1.5 V is joined across a resistor. What is its resistance (in ohms)?
22. 22.📏 How many kilowatts (kW) is 1450 W? =
23. 23.📏 In the water-pipe picture of a circuit, voltage is like … (a) the tap handle (b) the pipe colour (c) the water pressure (d) the water tank lid
24. 24.💡 Does it save or waste electricity to leave the TV on standby? (a) saves electricity (b) wastes electricity
25. 25.⚡ A device works on 1.5 V and takes 0.2 A. What is its power (in watts)? =
26. 26.🧮 Two equal 50 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
27. 27.🔺 A 5 V supply is joined across a 20 Ω resistor. What current flows (in amperes)? =
28. 28.True or false: to switch off empty rooms wastes electricity. (a) True (b) False
29. 29.🧩 Which component blows if current is high? (a) fuse (b) motor (c) LED (d) capacitor
30. 30.True or false: a capacitor smooths a wobbly supply. (a) False (b) True
31. 31.🔺 A current of 2.5 A flows when 5 V is joined across a resistor. What is its resistance (in ohms)?
32. 32.⚡ Power tells us … (a) the length of a wire (b) energy used each second (c) the colour of light (d) the size of a cell
33. 33.🔺 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
34. 34.🌈 A resistor has the colour bands brown, red, brown. What is its value (in ohms)?
35. 35.True or false: the flow of charge is measured in ohms (Ω). (a) True (b) False
36. 36.📏 Which unit measures the push of a cell? (a) volt (V) (b) ohm (Ω) (c) watt (W) (d) ampere (A)
37. 37.📏 How many watts (W) is 3.6 kW?
38. 38.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) gets bigger (b) gets smaller (c) stays the same (d) becomes zero
39. 39.🧮 A 10 Ω resistor is joined in series with two equal 50 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
40. 40.⚡ A 7.5 W device works on 5 V. What current does it take (in amperes)? =

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