Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 687 · 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.💡 Does it save or waste electricity to run fans in empty rooms? (a) saves electricity (b) wastes electricity
2. 2.🌈 A gold fourth band on a resistor means the value may be off by … (a) 0 % (b) 5 % (c) 25 % (d) 50 %
3. 3.True or false: a resistor limits the current. (a) True (b) False
4. 4.🧩 Which component smooths a wobbly supply? (a) motor (b) LDR (c) capacitor (d) LED
5. 5.🔺 A current of 1 A flows when 8 V is joined across a resistor. What is its resistance (in ohms)?
6. 6.🔺 A current of 20 mA flows through a 150 Ω resistor. What is the voltage across it (in volts)? =
7. 7.🧮 Adding another resistor in series makes the total resistance … (a) smaller (b) bigger (c) stay the same (d) zero
8. 8.📏 Voltmeter or ammeter: which one is joined across a part? (a) ammeter (b) voltmeter
9. 9.⚡ A device works on 9 V and takes 0.5 A. What is its power (in watts)? =
10. 10.🔺 A current of 0.2 A flows through a 4 Ω resistor. What is the voltage across it (in volts)? =
11. 11.🧮 Two resistors in parallel give a total that is … (a) more than either one (b) less than either one (c) their sum (d) always zero
12. 12.🧮 Three equal 75 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
13. 13.⚡ Power tells us … (a) the length of a wire (b) the size of a cell (c) the colour of light (d) energy used each second
14. 14.⚡ A home appliance on the 230 V mains takes 4 A. What is its power (in watts)?
15. 15.🔺 A current of 10 mA flows when 3.3 V is joined across a resistor. What is its resistance (in ohms)?
16. 16.💡 Does it save or waste electricity to use daylight to read? (a) saves electricity (b) wastes electricity
17. 17.⚡ A home appliance on the 230 V mains takes 1.5 A. What is its power (in watts)?
18. 18.True or false: power is measured in amperes (A). (a) True (b) False
19. 19.🧩 Which component blows if current is high? (a) diode (b) fuse (c) resistor (d) capacitor
20. 20.🧾 A 60 W filament bulb is swapped for a 9 W LED lamp that gives about the same light. Both would run for 3 hours. How many watt-hours (Wh) are saved?
21. 21.🧮 A 14 V battery is joined to 6 Ω and 8 Ω resistors in series. What current flows (in amperes)? =
22. 22.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) gets bigger (b) becomes zero (c) gets smaller (d) stays the same
23. 23.🧮 Resistors of 47 Ω, 20 Ω and 22 Ω are joined in series. What is the total resistance (in ohms)?
24. 24.🧮 A 220 Ω resistor is joined in series with two equal 40 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
25. 25.🔺 A 5 V supply is joined across a 500 Ω resistor. What current flows (in milliamperes, mA)?
26. 26.🔺 A current of 3 A flows through a 2 Ω resistor. What is the voltage across it (in volts)? =
27. 27.Which of these is measured in ohms (Ω)? (a) voltage (b) resistance (c) the flow of charge (d) the push of a cell
28. 28.💡 Does it save or waste electricity to leave fridge door open? (a) saves electricity (b) wastes electricity
29. 29.💡 What happens if an LED is put in backwards? (a) it lights brighter (b) it changes colour (c) it does not light (d) it makes a sound
30. 30.🌈 A resistor has the colour bands white, yellow, orange. What is its value (in ohms)?
31. 31.💡 On an LED, is the leg by the flat edge the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
32. 32.True or false: on an LED, the leg by the flat edge is the anode (+). (a) True (b) False
33. 33.What does an LDR do? (a) smooths a wobbly supply (b) senses how bright it is (c) makes a beeping sound (d) beeps for an alarm
34. 34.🔺 A current of 1.5 A flows when 18 V is joined across a resistor. What is its resistance (in ohms)?
35. 35.🌈 In the resistor colour code, which number does orange stand for?
36. 36.🧮 A 330 Ω resistor is joined in series with two equal 10 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
37. 37.🔺 A current of 0.1 A flows when 0.4 V is joined across a resistor. What is its resistance (in ohms)?
38. 38.True or false: on an LED, the longer leg is the anode (+). (a) False (b) True
39. 39.📏 Which unit measures resistance? (a) watt (W) (b) volt (V) (c) ohm (Ω) (d) ampere (A)
40. 40.🔺 A current of 2.5 A flows when 15 V is joined across a resistor. What is its resistance (in ohms)?

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