Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 754 · 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: a resistor glows using little power. (a) True (b) False
2. 2.🧩 Which part changes electrical energy into movement? (a) a fuse (b) a resistor (c) an LED (d) a motor
3. 3.🔺 A current of 20 mA flows through a 330 Ω resistor. What is the voltage across it (in volts)? =
4. 4.🔺 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
5. 5.🧩 Which part changes electrical energy into sound? (a) a capacitor (b) a resistor (c) a diode (d) a buzzer
6. 6.🔺 A 4.4 V supply is joined across a 220 Ω resistor. What current flows (in milliamperes, mA)?
7. 7.🔺 A current of 50 mA flows through a 470 Ω resistor. What is the voltage across it (in volts)? =
8. 8.🔺 In the V-I-R triangle, how do we find R? (a) R = I ÷ V (b) R = V × I (c) R = V + I (d) R = V ÷ I
9. 9.⚡ A device works on 5 V and takes 0.1 A. What is its power (in watts)? =
10. 10.True or false: to switch off empty rooms wastes electricity. (a) True (b) False
11. 11.📏 Which unit measures current? (a) watt (W) (b) ohm (Ω) (c) volt (V) (d) ampere (A)
12. 12.🔺 A 10 V supply is joined across a 4 Ω resistor. What current flows (in amperes)? =
13. 13.True or false: on an LED, the longer leg is the anode (+). (a) False (b) True
14. 14.Which of these is measured in ohms (Ω)? (a) power (b) the push of a cell (c) resistance (d) voltage
15. 15.📏 Which unit measures energy used each second? (a) ohm (Ω) (b) volt (V) (c) ampere (A) (d) watt (W)
16. 16.🔺 A 2.4 V supply is joined across a 120 Ω resistor. What current flows (in milliamperes, mA)?
17. 17.🌈 A resistor has the colour bands violet, orange, red. What is its value (in ohms)?
18. 18.Which of these is measured in ohms (Ω)? (a) how much a part resists (b) power (c) energy used each second (d) the push of a cell
19. 19.True or false: how much a part resists is measured in ohms (Ω). (a) False (b) True
20. 20.📏 How many milliamperes (mA) is 2.97 A?
21. 21.True or false: to leave fridge door open saves electricity. (a) False (b) True
22. 22.🔺 A current of 10 mA flows when 4 V is joined across a resistor. What is its resistance (in ohms)?
23. 23.🔺 In the V-I-R triangle, how do we find I? (a) I = V ÷ R (b) I = V + R (c) I = V × R (d) I = R ÷ V
24. 24.🔺 A current of 2.5 A flows through a 20 Ω resistor. What is the voltage across it (in volts)? =
25. 25.⚡ A device works on 12 V and takes 1.5 A. What is its power (in watts)? =
26. 26.💡 On an LED, is the longer leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
27. 27.🧮 Two equal 220 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
28. 28.🌈 In the resistor colour code, which number does black stand for?
29. 29.🧮 Two resistors in parallel give a total that is … (a) less than either one (b) more than either one (c) always zero (d) their sum
30. 30.📏 Voltmeter or ammeter: which one is joined in series? (a) ammeter (b) voltmeter
31. 31.🧩 Which component makes a beeping sound? (a) fuse (b) potentiometer (c) LED (d) buzzer
32. 32.🔺 A current of 1 A flows through an 8 Ω resistor. What is the voltage across it (in volts)? =
33. 33.💡 Does it save or waste electricity to leave fridge door open? (a) saves electricity (b) wastes electricity
34. 34.True or false: to set the AC to 24 °C wastes electricity. (a) False (b) True
35. 35.🧾 A 100 W appliance runs for 2 hours. How many units (kWh) of electricity does it use? =
36. 36.🌈 A resistor has the colour bands orange, blue, red. What is its value (in ohms)?
37. 37.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) stays the same (b) gets bigger (c) becomes zero (d) gets smaller
38. 38.📏 Voltmeter or ammeter: which one is joined across a part? (a) ammeter (b) voltmeter
39. 39.🧩 Which component smooths a wobbly supply? (a) diode (b) motor (c) capacitor (d) fuse
40. 40.🌈 A gold fourth band on a resistor means the value may be off by … (a) 0 % (b) 50 % (c) 25 % (d) 5 %

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