Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 365 · 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 current of 0.25 A flows through an 8 Ω resistor. What is the voltage across it (in volts)? =
2. 2.🔺 In the V-I-R triangle, how do we find V? (a) V = I × R (b) V = R ÷ I (c) V = I ÷ R (d) V = I + R
3. 3.📏 How many milliamperes (mA) make 1 ampere? (a) 1000 (b) 60 (c) 10 (d) 100
4. 4.True or false: on an LED, the round-side leg is the cathode (−). (a) True (b) False
5. 5.💡 On an LED, is the leg by the flat edge the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
6. 6.🧾 A 40 W filament bulb is swapped for a 6 W LED lamp that gives about the same light. Both would run for 6 hours. How many watt-hours (Wh) are saved?
7. 7.🧮 Two resistors in parallel give a total that is … (a) less than either one (b) more than either one (c) their sum (d) always zero
8. 8.📏 How many ohms (Ω) is 2.8 kΩ?
9. 9.🔺 A current of 1.5 A flows through an 8 Ω resistor. What is the voltage across it (in volts)? =
10. 10.⚡ A device works on 1.5 V and takes 0.25 A. What is its power (in watts)? =
11. 11.⚡ Power tells us … (a) the size of a cell (b) energy used each second (c) the length of a wire (d) the colour of light
12. 12.💡 Does it save or waste electricity to set the AC to 24 °C? (a) wastes electricity (b) saves electricity
13. 13.🌈 Which band is read first on a resistor? (a) the gold band (b) any band (c) the widest gap (d) the one nearest an end
14. 14.📏 How many amperes (A) is 2280 mA? =
15. 15.🌈 A resistor has the colour bands green, black, orange. What is its value in kilo-ohms (kΩ)? =
16. 16.🧮 Four equal 40 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
17. 17.💡 On an LED, is the longer leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
18. 18.🧮 Five equal 500 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
19. 19.True or false: the push of a cell is measured in watts (W). (a) False (b) True
20. 20.🧾 A 75 W filament bulb is swapped for a 12 W LED lamp that gives about the same light. Both would run for 2 hours. How many watt-hours (Wh) are saved?
21. 21.Which of these is measured in volts (V)? (a) resistance (b) current (c) the push of a cell (d) how much a part resists
22. 22.📏 How many ohms make 1 kilo-ohm (kΩ)? (a) 1000 (b) 100 (c) 1024 (d) 10
23. 23.True or false: to close the fridge quickly saves electricity. (a) False (b) True
24. 24.📏 Voltmeter or ammeter: which one measures voltage? (a) voltmeter (b) ammeter
25. 25.🔺 A 3.3 V supply is joined across a 330 Ω resistor. What current flows (in milliamperes, mA)?
26. 26.⚡ A 6 W device works on 6 V. What current does it take (in amperes)? =
27. 27.🧾 Which lamp gives the same light for the least power? (a) a candle (b) a filament bulb (c) an LED lamp (d) an oil lamp
28. 28.🌈 A gold fourth band on a resistor means the value may be off by … (a) 50 % (b) 5 % (c) 0 % (d) 25 %
29. 29.🔺 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
30. 30.🧩 Which component is a resistance knob? (a) thermistor (b) buzzer (c) potentiometer (d) motor
31. 31.⚡ A 1.2 W device works on 12 V. What current does it take (in amperes)? =
32. 32.🔺 A 6 V supply is joined across a 12 Ω resistor. What current flows (in amperes)? =
33. 33.True or false: a motor makes things spin. (a) False (b) True
34. 34.🧮 Adding another resistor in series makes the total resistance … (a) bigger (b) zero (c) smaller (d) stay the same
35. 35.⚡ A device works on 9 V and takes 1.5 A. What is its power (in watts)? =
36. 36.What does a capacitor do? (a) smooths a wobbly supply (b) senses how bright it is (c) makes a beeping sound (d) glows using little power
37. 37.🧩 Which component makes things spin? (a) diode (b) motor (c) LED (d) resistor
38. 38.🧾 A 40 W filament bulb is swapped for a 6 W LED lamp that gives about the same light. Both would run for 9 hours. How many watt-hours (Wh) are saved?
39. 39.🌈 In the resistor colour code, which number does white stand for?
40. 40.⚡ A home appliance on the 230 V mains takes 0.5 A. What is its power (in watts)?

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