Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 608 · 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 resistor has the colour bands red, green, orange. What is its value (in ohms)?
2. 2.🔺 A current of 0.25 A flows through a 2 Ω resistor. What is the voltage across it (in volts)? =
3. 3.⚡ Power tells us … (a) energy used each second (b) the size of a cell (c) the colour of light (d) the length of a wire
4. 4.🔺 In the V-I-R triangle, how do we find I? (a) I = V × R (b) I = V ÷ R (c) I = R ÷ V (d) I = V + R
5. 5.🌈 In the resistor colour code, which number does white stand for?
6. 6.🧮 Three equal 75 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
7. 7.📏 How many ohms (Ω) is 1.8 kΩ?
8. 8.🧾 Which lamp gives the same light for the least power? (a) an oil lamp (b) a candle (c) an LED lamp (d) a filament bulb
9. 9.🔺 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
10. 10.📏 How many ohms (Ω) is 0.5 kΩ?
11. 11.🌈 A gold fourth band on a resistor means the value may be off by … (a) 0 % (b) 50 % (c) 25 % (d) 5 %
12. 12.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 14 Ω resistor? (a) yellow-brown-black (b) red-yellow-black (c) brown-yellow-black (d) brown-yellow-brown
13. 13.🔺 A 1 V supply is joined across a 2 Ω resistor. What current flows (in amperes)? =
14. 14.💡 On an LED, is the shorter leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
15. 15.💡 On an LED, is the longer leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
16. 16.💡 A red LED (it uses 2 V) is joined with a 150 Ω resistor to a 2.75 V supply. What current flows (in mA)?
17. 17.Which of these is measured in ohms (Ω)? (a) current (b) the flow of charge (c) voltage (d) resistance
18. 18.🧮 Five equal 500 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
19. 19.🔺 A current of 40 mA flows when 18.8 V is joined across a resistor. What is its resistance (in ohms)?
20. 20.📏 Which unit measures current? (a) volt (V) (b) watt (W) (c) ampere (A) (d) ohm (Ω)
21. 21.📏 Which unit measures the push of a cell? (a) volt (V) (b) watt (W) (c) ohm (Ω) (d) ampere (A)
22. 22.🔺 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
23. 23.🔺 A current of 0.25 A flows when 1.25 V is joined across a resistor. What is its resistance (in ohms)?
24. 24.💡 Does it save or waste electricity to unplug idle chargers? (a) wastes electricity (b) saves electricity
25. 25.🔺 A current of 40 mA flows through a 300 Ω resistor. What is the voltage across it (in volts)? =
26. 26.🧩 Which component smooths a wobbly supply? (a) resistor (b) transistor (c) LDR (d) capacitor
27. 27.🔺 A current of 0.25 A flows through a 15 Ω resistor. What is the voltage across it (in volts)? =
28. 28.🔺 A 2.5 V supply is joined across a 5 Ω resistor. What current flows (in amperes)? =
29. 29.🧩 A capacitor in a circuit can … (a) make light (b) store charge briefly (c) measure heat (d) spin a wheel
30. 30.🧾 One “unit” on an electricity bill is … (a) 1 kilowatt-hour (kWh) (b) 1 volt (c) 1 ampere (d) 1 watt
31. 31.Which of these saves electricity? (a) unplug idle chargers (b) run fans in empty rooms (c) leave fridge door open (d) iron one shirt at a time
32. 32.🔺 A current of 2 A flows when 30 V is joined across a resistor. What is its resistance (in ohms)?
33. 33.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) becomes zero (b) gets smaller (c) gets bigger (d) stays the same
34. 34.🔺 A current of 1.5 A flows when 12 V is joined across a resistor. What is its resistance (in ohms)?
35. 35.📏 How many milliamperes (mA) is 1.79 A?
36. 36.🌈 Which band is read first on a resistor? (a) the widest gap (b) the one nearest an end (c) the gold band (d) any band
37. 37.🧩 Which part changes electrical energy into movement? (a) a fuse (b) an LED (c) a motor (d) a resistor
38. 38.Which of these saves electricity? (a) switch off empty rooms (b) iron one shirt at a time (c) run fans in empty rooms (d) use old filament bulbs
39. 39.🧾 A 500 W appliance runs for 6 hours. How many units (kWh) of electricity does it use? =
40. 40.🔍 Which is the odd one out? (a) close the fridge quickly (b) set the AC to 24 °C (c) use LED lamps (d) leave fridge door open

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