Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 538 · 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.🔺 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
2. 2.🧮 Resistors of 33 Ω, 150 Ω, 10 Ω and 10 Ω are joined in series. What is the total resistance (in ohms)?
3. 3.🧾 A 2000 W appliance runs for 4 hours. How many units (kWh) of electricity does it use? =
4. 4.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) stays the same (b) gets smaller (c) gets bigger (d) becomes zero
5. 5.True or false: to unplug idle chargers saves electricity. (a) False (b) True
6. 6.🧮 A 33 Ω resistor is joined in series with two equal 50 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
7. 7.🔺 In the V-I-R triangle, how do we find V? (a) V = R ÷ I (b) V = I ÷ R (c) V = I + R (d) V = I × R
8. 8.📏 Which unit measures how much a part resists? (a) watt (W) (b) ohm (Ω) (c) ampere (A) (d) volt (V)
9. 9.🔺 A current of 0.5 A flows through a 2 Ω resistor. What is the voltage across it (in volts)? =
10. 10.📏 In the water-pipe picture of a circuit, resistance is like … (a) a narrow pipe (b) a bigger tank (c) the flow of water (d) the water pressure
11. 11.💡 A blue LED uses 3 V and should get 25 mA. It runs from a 6 V supply. What resistor (in ohms) is needed in series?
12. 12.🌈 Which band is read first on a resistor? (a) the gold band (b) the one nearest an end (c) the widest gap (d) any band
13. 13.🧮 Two equal 50 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
14. 14.📏 How many kilo-ohms (kΩ) is 1800 Ω? =
15. 15.Which of these saves electricity? (a) run fans in empty rooms (b) iron one shirt at a time (c) close the fridge quickly (d) leave fridge door open
16. 16.⚡ A device works on 24 V and takes 3 A. What is its power (in watts)? =
17. 17.🧾 A family uses 170 units of electricity in a month and each unit costs ₹4. What is the bill (in ₹)?
18. 18.True or false: the ammeter is joined across a part. (a) False (b) True
19. 19.📏 Voltmeter or ammeter: which one measures current? (a) voltmeter (b) ammeter
20. 20.💡 What happens if an LED is put in backwards? (a) it makes a sound (b) it lights brighter (c) it does not light (d) it changes colour
21. 21.🧾 A 200 W appliance runs for 2 hours. How many units (kWh) of electricity does it use? =
22. 22.🧮 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
23. 23.🌈 A resistor has the colour bands grey, brown, yellow. What is its value in kilo-ohms (kΩ)? =
24. 24.What does an LDR do? (a) makes a beeping sound (b) blows if current is high (c) smooths a wobbly supply (d) senses how bright it is
25. 25.🧾 A 50 W appliance runs for 8 hours. How many units (kWh) of electricity does it use? =
26. 26.True or false: a fuse blows if current is high. (a) False (b) True
27. 27.🔺 A current of 0.5 A flows through a 3 Ω resistor. What is the voltage across it (in volts)? =
28. 28.🧮 A 470 Ω resistor is joined in series with two equal 20 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
29. 29.🧩 Which component makes a beeping sound? (a) LED (b) buzzer (c) fuse (d) potentiometer
30. 30.📏 How many amperes (A) is 1290 mA? =
31. 31.🔺 A current of 1.5 A flows through a 5 Ω resistor. What is the voltage across it (in volts)? =
32. 32.🧩 A capacitor in a circuit can … (a) make light (b) spin a wheel (c) measure heat (d) store charge briefly
33. 33.🔺 A current of 2.5 A flows when 37.5 V is joined across a resistor. What is its resistance (in ohms)?
34. 34.💡 On an LED, is the round-side leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
35. 35.🔺 A 7.5 V supply is joined across a 150 Ω resistor. What current flows (in milliamperes, mA)?
36. 36.True or false: to run fans in empty rooms wastes electricity. (a) True (b) False
37. 37.🔺 A current of 2 A flows when 16 V is joined across a resistor. What is its resistance (in ohms)?
38. 38.📏 How many milliamperes (mA) make 1 ampere? (a) 100 (b) 60 (c) 1000 (d) 10
39. 39.🌈 A resistor has the colour bands brown, brown, red. What is its value in kilo-ohms (kΩ)? =
40. 40.🌈 A gold fourth band on a resistor means the value may be off by … (a) 25 % (b) 50 % (c) 0 % (d) 5 %

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