Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 626 · 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.📏 How many watts (W) is 0.3 kW?
2. 2.🔺 A current of 0.5 A flows through a 20 Ω resistor. What is the voltage across it (in volts)? =
3. 3.True or false: to unplug idle chargers wastes electricity. (a) True (b) False
4. 4.🧮 A 22 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)?
5. 5.🔺 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
6. 6.True or false: on an LED, the round-side leg is the cathode (−). (a) True (b) False
7. 7.True or false: on an LED, the longer leg is the cathode (−). (a) True (b) False
8. 8.🔺 A current of 0.1 A flows when 0.2 V is joined across a resistor. What is its resistance (in ohms)?
9. 9.💡 Why does an LED need a resistor in series? (a) to make it brighter (b) to change its colour (c) to limit the current (d) to store charge
10. 10.🔺 A current of 0.5 A flows through a 6 Ω resistor. What is the voltage across it (in volts)? =
11. 11.🧩 A capacitor in a circuit can … (a) spin a wheel (b) make light (c) measure heat (d) store charge briefly
12. 12.🌈 A resistor has the colour bands orange, yellow, black. What is its value (in ohms)?
13. 13.🧮 A 4.5 V battery is joined to 4 Ω and 5 Ω resistors in series. What current flows (in amperes)? =
14. 14.🌈 A gold fourth band on a resistor means the value may be off by … (a) 5 % (b) 0 % (c) 25 % (d) 50 %
15. 15.📏 How many amperes (A) is 190 mA? =
16. 16.🧾 One “unit” on an electricity bill is … (a) 1 watt (b) 1 ampere (c) 1 kilowatt-hour (kWh) (d) 1 volt
17. 17.🔺 A current of 0.5 A flows when 1 V is joined across a resistor. What is its resistance (in ohms)?
18. 18.🔺 A current of 3 A flows through a 10 Ω resistor. What is the voltage across it (in volts)? =
19. 19.🧮 Two resistors in parallel give a total that is … (a) more than either one (b) always zero (c) less than either one (d) their sum
20. 20.💡 Does it save or waste electricity to use LED lamps? (a) saves electricity (b) wastes electricity
21. 21.🧩 Which component has coloured bands? (a) fuse (b) resistor (c) motor (d) LED
22. 22.🌈 In the resistor colour code, which number does brown stand for?
23. 23.🔺 A current of 40 mA flows when 8 V is joined across a resistor. What is its resistance (in ohms)?
24. 24.🧮 Four equal 40 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
25. 25.🔺 A current of 0.2 A flows when 3 V is joined across a resistor. What is its resistance (in ohms)?
26. 26.🔺 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
27. 27.⚡ A home appliance on the 230 V mains takes 1.5 A. What is its power (in watts)?
28. 28.📏 How many milliamperes (mA) is 0.97 A?
29. 29.🌈 Which band is read first on a resistor? (a) the widest gap (b) the one nearest an end (c) any band (d) the gold band
30. 30.🔺 A current of 25 mA flows through a 220 Ω resistor. What is the voltage across it (in volts)? =
31. 31.🧾 Which lamp gives the same light for the least power? (a) a filament bulb (b) an oil lamp (c) an LED lamp (d) a candle
32. 32.🧮 A 10 Ω resistor is joined in series with two equal 10 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
33. 33.⚡ A home appliance on the 230 V mains takes 2 A. What is its power (in watts)?
34. 34.🔍 Which is the odd one out? (a) run fans in empty rooms (b) use LED lamps (c) leave fridge door open (d) leave the TV on standby
35. 35.🧮 Four equal 100 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
36. 36.What does an LED do? (a) glows using little power (b) smooths a wobbly supply (c) turns a fan or wheels (d) is a resistance knob
37. 37.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) gets smaller (b) stays the same (c) gets bigger (d) becomes zero
38. 38.🔺 A current of 40 mA flows when 8.8 V is joined across a resistor. What is its resistance (in ohms)?
39. 39.🔍 Which is the odd one out? (a) close the fridge quickly (b) set the AC to 24 °C (c) use daylight to read (d) leave fridge door open
40. 40.📏 How many watts (W) is 0.8 kW?

Free electronics lessons, practice and worksheets at talentjr.in/electronics-for-kids