Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 831 · 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.True or false: a thermistor smooths a wobbly supply. (a) False (b) True
2. 2.🔺 In the V-I-R triangle, how do we find I? (a) I = V × R (b) I = V ÷ R (c) I = V + R (d) I = R ÷ V
3. 3.📏 Voltmeter or ammeter: which one measures current? (a) voltmeter (b) ammeter
4. 4.🔺 A current of 0.5 A flows through a 3 Ω resistor. What is the voltage across it (in volts)? =
5. 5.⚡ Power tells us … (a) the length of a wire (b) the size of a cell (c) energy used each second (d) the colour of light
6. 6.Which of these is measured in volts (V)? (a) the flow of charge (b) current (c) voltage (d) power
7. 7.🧩 Which component lets current go one way? (a) capacitor (b) resistor (c) LED (d) diode
8. 8.📏 In the water-pipe picture of a circuit, voltage is like … (a) the tap handle (b) the water tank lid (c) the water pressure (d) the pipe colour
9. 9.🔺 A current of 0.25 A flows when 2.5 V is joined across a resistor. What is its resistance (in ohms)?
10. 10.🔺 A current of 1 A flows through a 2 Ω resistor. What is the voltage across it (in volts)? =
11. 11.🧩 Which component stores a little charge? (a) motor (b) capacitor (c) potentiometer (d) buzzer
12. 12.🔺 A current of 1 A flows when 10 V is joined across a resistor. What is its resistance (in ohms)?
13. 13.🧩 Which component is a resistance knob? (a) buzzer (b) LED (c) potentiometer (d) fuse
14. 14.💡 On an LED, is the shorter leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
15. 15.🌈 A resistor has the colour bands red, violet, red. What is its value (in ohms)?
16. 16.🧮 Adding another resistor in series makes the total resistance … (a) stay the same (b) zero (c) bigger (d) smaller
17. 17.🔺 A current of 0.2 A flows when 0.4 V is joined across a resistor. What is its resistance (in ohms)?
18. 18.True or false: an LED glows using little power. (a) False (b) True
19. 19.🔺 A current of 0.25 A flows when 2 V is joined across a resistor. What is its resistance (in ohms)?
20. 20.🔺 A 2.5 V supply is joined across a 10 Ω resistor. What current flows (in amperes)? =
21. 21.⚡ A device works on 1.5 V and takes 2 A. What is its power (in watts)? =
22. 22.🔍 Which is the odd one out? (a) leave the TV on standby (b) leave fridge door open (c) run fans in empty rooms (d) use LED lamps
23. 23.🔺 A current of 1.5 A flows through a 6 Ω resistor. What is the voltage across it (in volts)? =
24. 24.🧮 Resistors of 470 Ω and 68 Ω are joined in series. What is the total resistance (in ohms)?
25. 25.🧮 Two equal 10 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
26. 26.⚡ Which formula gives electric power? (a) P = V ÷ I (b) P = I ÷ V (c) P = V + I (d) P = V × I
27. 27.🔺 An 8 V supply is joined across a 200 Ω resistor. What current flows (in milliamperes, mA)?
28. 28.Which of these is measured in ohms (Ω)? (a) the flow of charge (b) resistance (c) current (d) voltage
29. 29.🧮 A 10 Ω resistor is joined in series with two equal 20 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
30. 30.🔺 A current of 25 mA flows through a 100 Ω resistor. What is the voltage across it (in volts)? =
31. 31.True or false: to run fans in empty rooms saves electricity. (a) False (b) True
32. 32.🌈 A gold fourth band on a resistor means the value may be off by … (a) 25 % (b) 5 % (c) 0 % (d) 50 %
33. 33.🔺 A current of 0.2 A flows through a 20 Ω resistor. What is the voltage across it (in volts)? =
34. 34.🧩 Which component has coloured bands? (a) potentiometer (b) LDR (c) buzzer (d) resistor
35. 35.🔺 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
36. 36.💡 What does LED stand for? (a) large electric dial (b) light energy dial (c) light-emitting diode (d) low energy device
37. 37.What does a fuse do? (a) makes a beeping sound (b) blows if current is high (c) smooths a wobbly supply (d) senses how hot it is
38. 38.🧩 Which component blows if current is high? (a) thermistor (b) fuse (c) buzzer (d) diode
39. 39.🔺 A current of 2.5 A flows through a 12 Ω resistor. What is the voltage across it (in volts)? =
40. 40.💡 Does it save or waste electricity to use daylight to read? (a) saves electricity (b) wastes electricity

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