Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 193 · 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.💡 On an LED, is the longer leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
2. 2.🌈 A resistor has the colour bands white, violet, orange. What is its value in kilo-ohms (kΩ)? =
3. 3.🧮 Two equal 330 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
4. 4.💡 Does it save or waste electricity to use daylight to read? (a) wastes electricity (b) saves electricity
5. 5.🔺 A current of 10 mA flows through a 120 Ω resistor. What is the voltage across it (in volts)? =
6. 6.🧩 Which component turns a fan or wheels? (a) potentiometer (b) LED (c) fuse (d) motor
7. 7.⚡ A home appliance on the 230 V mains takes 0.5 A. What is its power (in watts)?
8. 8.⚡ A home appliance on the 230 V mains takes 4 A. What is its power (in watts)?
9. 9.Which of these is measured in volts (V)? (a) power (b) the push of a cell (c) resistance (d) current
10. 10.🧩 Which component glows using little power? (a) resistor (b) diode (c) LED (d) thermistor
11. 11.⚡ A home appliance on the 230 V mains takes 10 A. What is its power (in watts)?
12. 12.⚡ A device works on 1.5 V and takes 0.5 A. What is its power (in watts)? =
13. 13.🔺 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
14. 14.🔺 A current of 20 mA flows when 2 V is joined across a resistor. What is its resistance (in ohms)?
15. 15.🧾 A 1000 W appliance runs for 10 hours. How many units (kWh) of electricity does it use? =
16. 16.💡 An LED is joined to a 5 V battery with no resistor; its long leg goes to the + side and its short leg to the − side. What happens? (a) lights up (b) may burn out (c) does not light
17. 17.💡 A red LED (it uses 2 V) is joined with a 150 Ω resistor to a 5 V supply. What current flows (in mA)?
18. 18.🔺 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
19. 19.⚡ A 0.3 W device works on 3 V. What current does it take (in amperes)? =
20. 20.🧾 A 1500 W appliance runs for 2 hours. How many units (kWh) of electricity does it use? =
21. 21.🔺 A current of 0.5 A flows when 1.5 V is joined across a resistor. What is its resistance (in ohms)?
22. 22.Which of these wastes electricity? (a) use LED lamps (b) use daylight to read (c) leave fridge door open (d) close the fridge quickly
23. 23.🔺 A 1 V supply is joined across a 2 Ω resistor. What current flows (in amperes)? =
24. 24.💡 On an LED, is the shorter leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
25. 25.🧮 Resistors of 10 Ω and 150 Ω are joined in series. What is the total resistance (in ohms)?
26. 26.💡 What does LED stand for? (a) large electric dial (b) low energy device (c) light energy dial (d) light-emitting diode
27. 27.🌈 A gold fourth band on a resistor means the value may be off by … (a) 50 % (b) 25 % (c) 5 % (d) 0 %
28. 28.📏 How many watts (W) is 5 kW?
29. 29.🧩 A capacitor in a circuit can … (a) make light (b) spin a wheel (c) store charge briefly (d) measure heat
30. 30.📏 Voltmeter or ammeter: which one is joined across a part? (a) ammeter (b) voltmeter
31. 31.🧮 A 10 V battery is joined to 8 Ω and 2 Ω resistors in series. What current flows (in amperes)? =
32. 32.🧮 Adding another resistor in series makes the total resistance … (a) stay the same (b) zero (c) bigger (d) smaller
33. 33.What does a fuse do? (a) blows if current is high (b) makes a beeping sound (c) glows using little power (d) beeps for an alarm
34. 34.🔺 A current of 40 mA flows when 4.8 V is joined across a resistor. What is its resistance (in ohms)?
35. 35.🔺 A 10 V supply is joined across a 5 Ω resistor. What current flows (in amperes)? =
36. 36.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 3900 Ω resistor? (a) orange-white-red (b) white-orange-red (c) orange-white-brown (d) orange-white-orange
37. 37.🔺 A current of 25 mA flows through a 470 Ω resistor. What is the voltage across it (in volts)? =
38. 38.📏 In the water-pipe picture of a circuit, current is like … (a) the pipe colour (b) the water pressure (c) a narrow pipe (d) the flow of water
39. 39.🔺 A current of 25 mA flows through a 330 Ω resistor. What is the voltage across it (in volts)? =
40. 40.🧮 Four equal 200 Ω resistors are joined in parallel. What is the total resistance (in ohms)?

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