Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 891 · 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: the push of a cell is measured in watts (W). (a) False (b) True
2. 2.🧮 Resistors of 68 Ω and 22 Ω are joined in series. What is the total resistance (in ohms)?
3. 3.🧮 Four equal 100 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
4. 4.True or false: to close the fridge quickly saves electricity. (a) True (b) False
5. 5.🌈 A resistor has the colour bands white, brown, yellow. What is its value in kilo-ohms (kΩ)? =
6. 6.🧩 Which component beeps for an alarm? (a) capacitor (b) fuse (c) motor (d) buzzer
7. 7.🔺 A 5 V supply is joined across a 10 Ω resistor. What current flows (in amperes)? =
8. 8.🔍 Which is the odd one out? (a) run fans in empty rooms (b) leave the TV on standby (c) use old filament bulbs (d) set the AC to 24 °C
9. 9.🔺 In the V-I-R triangle, how do we find V? (a) V = I ÷ R (b) V = I + R (c) V = R ÷ I (d) V = I × R
10. 10.⚡ A home appliance on the 230 V mains takes 1 A. What is its power (in watts)?
11. 11.💡 On an LED, is the round-side leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
12. 12.🧮 Adding another resistor in series makes the total resistance … (a) bigger (b) smaller (c) stay the same (d) zero
13. 13.🔺 In the V-I-R triangle, how do we find R? (a) R = V ÷ I (b) R = V × I (c) R = I ÷ V (d) R = V + I
14. 14.🔺 A current of 2 A flows when 24 V is joined across a resistor. What is its resistance (in ohms)?
15. 15.🔺 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
16. 16.🧾 Which lamp gives the same light for the least power? (a) a candle (b) a filament bulb (c) an oil lamp (d) an LED lamp
17. 17.🔺 A 5.5 V supply is joined across a 220 Ω resistor. What current flows (in milliamperes, mA)?
18. 18.⚡ A device works on 12 V and takes 0.2 A. What is its power (in watts)? =
19. 19.True or false: power is measured in watts (W). (a) True (b) False
20. 20.🔍 Which is the odd one out? (a) unplug idle chargers (b) use daylight to read (c) use LED lamps (d) use old filament bulbs
21. 21.📏 Which unit measures current? (a) volt (V) (b) ampere (A) (c) ohm (Ω) (d) watt (W)
22. 22.🔺 A current of 0.2 A flows when 2.4 V is joined across a resistor. What is its resistance (in ohms)?
23. 23.Which of these is measured in watts (W)? (a) resistance (b) the flow of charge (c) current (d) energy used each second
24. 24.🧮 Two equal 10 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
25. 25.What does a thermistor do? (a) smooths a wobbly supply (b) turns a fan or wheels (c) stores a little charge (d) senses how hot it is
26. 26.True or false: a capacitor smooths a wobbly supply. (a) False (b) True
27. 27.💡 A red LED uses 2 V and should get 10 mA. It runs from a 9 V supply. What resistor (in ohms) is needed in series?
28. 28.🧩 Which part changes electrical energy into movement? (a) a fuse (b) a resistor (c) a motor (d) an LED
29. 29.True or false: the ammeter measures current. (a) False (b) True
30. 30.🌈 Which band is read first on a resistor? (a) any band (b) the gold band (c) the widest gap (d) the one nearest an end
31. 31.🧩 A capacitor in a circuit can … (a) store charge briefly (b) spin a wheel (c) make light (d) measure heat
32. 32.🔺 A current of 3 A flows through a 10 Ω resistor. What is the voltage across it (in volts)? =
33. 33.🧮 Two equal 470 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
34. 34.⚡ A device works on 5 V and takes 3 A. What is its power (in watts)? =
35. 35.⚡ A 0.75 W device works on 1.5 V. What current does it take (in amperes)? =
36. 36.What does a fuse do? (a) stores a little charge (b) blows if current is high (c) makes a beeping sound (d) senses how bright it is
37. 37.🔺 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
38. 38.🧩 Which component makes a beeping sound? (a) thermistor (b) buzzer (c) LED (d) motor
39. 39.📏 Which unit measures the flow of charge? (a) volt (V) (b) ampere (A) (c) watt (W) (d) ohm (Ω)
40. 40.True or false: a capacitor stores a little charge. (a) False (b) True

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