Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 723 · 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 volts (V)? (a) energy used each second (b) voltage (c) current (d) power
2. 2.🔺 In the V-I-R triangle, how do we find V? (a) V = I ÷ R (b) V = I × R (c) V = I + R (d) V = R ÷ I
3. 3.🧩 A capacitor in a circuit can … (a) make light (b) measure heat (c) spin a wheel (d) store charge briefly
4. 4.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) stays the same (b) becomes zero (c) gets bigger (d) gets smaller
5. 5.True or false: power is measured in watts (W). (a) True (b) False
6. 6.Which of these saves electricity? (a) leave fridge door open (b) unplug idle chargers (c) leave the TV on standby (d) run fans in empty rooms
7. 7.💡 A blue LED uses 3 V and should get 10 mA. It runs from a 6 V supply. What resistor (in ohms) is needed in series?
8. 8.🧮 Adding another resistor in series makes the total resistance … (a) zero (b) stay the same (c) bigger (d) smaller
9. 9.🔺 A current of 2 A flows through a 4 Ω resistor. What is the voltage across it (in volts)? =
10. 10.🔺 A current of 50 mA flows when 23.5 V is joined across a resistor. What is its resistance (in ohms)?
11. 11.True or false: how much a part resists is measured in ohms (Ω). (a) False (b) True
12. 12.🌈 A resistor has the colour bands blue, red, red. What is its value (in ohms)?
13. 13.⚡ Power tells us … (a) the size of a cell (b) the colour of light (c) the length of a wire (d) energy used each second
14. 14.⚡ A 0.3 W device works on 1.5 V. What current does it take (in amperes)? =
15. 15.🧮 Resistors of 470 Ω and 22 Ω are joined in series. What is the total resistance (in ohms)?
16. 16.📏 Voltmeter or ammeter: which one measures voltage? (a) ammeter (b) voltmeter
17. 17.⚡ A home appliance on the 230 V mains takes 4 A. What is its power (in watts)?
18. 18.🧮 A 5 V battery is joined to 8 Ω and 12 Ω resistors in series. What current flows (in amperes)? =
19. 19.⚡ Which formula gives electric power? (a) P = V × I (b) P = I ÷ V (c) P = V + I (d) P = V ÷ I
20. 20.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 3300 Ω resistor? (a) orange-orange-brown (b) orange-orange-red (c) orange-orange-orange (d) orange-yellow-red
21. 21.💡 What does LED stand for? (a) low energy device (b) light energy dial (c) light-emitting diode (d) large electric dial
22. 22.🧮 A 1.8 V battery is joined to 6 Ω and 12 Ω resistors in series. What current flows (in amperes)? =
23. 23.🧾 One “unit” on an electricity bill is … (a) 1 ampere (b) 1 volt (c) 1 kilowatt-hour (kWh) (d) 1 watt
24. 24.True or false: power is measured in amperes (A). (a) False (b) True
25. 25.🧩 Which component senses how hot it is? (a) LDR (b) thermistor (c) fuse (d) diode
26. 26.🌈 A resistor has the colour bands yellow, violet, black. What is its value (in ohms)?
27. 27.Which of these is measured in ohms (Ω)? (a) power (b) energy used each second (c) the flow of charge (d) how much a part resists
28. 28.🔺 A 0.8 V supply is joined across an 8 Ω resistor. What current flows (in amperes)? =
29. 29.⚡ A 6 W device works on 12 V. What current does it take (in amperes)? =
30. 30.🧮 Resistors of 22 Ω, 470 Ω, 47 Ω and 33 Ω are joined in series. What is the total resistance (in ohms)?
31. 31.📏 How many ohms make 1 kilo-ohm (kΩ)? (a) 1000 (b) 100 (c) 1024 (d) 10
32. 32.🧮 Two resistors in parallel give a total that is … (a) always zero (b) less than either one (c) more than either one (d) their sum
33. 33.Which of these is measured in watts (W)? (a) current (b) the push of a cell (c) energy used each second (d) resistance
34. 34.True or false: on an LED, the round-side leg is the cathode (−). (a) True (b) False
35. 35.🔺 A current of 20 mA flows through a 220 Ω resistor. What is the voltage across it (in volts)? =
36. 36.💡 Does it save or waste electricity to use old filament bulbs? (a) wastes electricity (b) saves electricity
37. 37.📏 In the water-pipe picture of a circuit, resistance is like … (a) a bigger tank (b) the water pressure (c) a narrow pipe (d) the flow of water
38. 38.📏 Which unit measures resistance? (a) volt (V) (b) watt (W) (c) ohm (Ω) (d) ampere (A)
39. 39.🌈 A resistor has the colour bands white, brown, black. What is its value (in ohms)?
40. 40.💡 What happens if an LED is put in backwards? (a) it lights brighter (b) it makes a sound (c) it changes colour (d) it does not light

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