Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 582 · 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 current of 10 mA flows when 1 V is joined across a resistor. What is its resistance (in ohms)?
2. 2.🧮 Resistors of 220 Ω, 50 Ω and 20 Ω are joined in series. What is the total resistance (in ohms)?
3. 3.🌈 In the resistor colour code, which number does red stand for?
4. 4.🧾 One “unit” on an electricity bill is … (a) 1 watt (b) 1 ampere (c) 1 kilowatt-hour (kWh) (d) 1 volt
5. 5.🔺 A current of 10 mA flows through a 220 Ω resistor. What is the voltage across it (in volts)? =
6. 6.🔺 A 1 V supply is joined across a 10 Ω resistor. What current flows (in amperes)? =
7. 7.🧮 A 470 Ω resistor is joined in series with two equal 1000 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
8. 8.💡 Does it save or waste electricity to switch off empty rooms? (a) wastes electricity (b) saves electricity
9. 9.True or false: to use old filament bulbs wastes electricity. (a) False (b) True
10. 10.🔺 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
11. 11.What does a fuse do? (a) limits the current (b) smooths a wobbly supply (c) blows if current is high (d) senses how bright it is
12. 12.🔺 A current of 1 A flows through a 12 Ω resistor. What is the voltage across it (in volts)? =
13. 13.True or false: a potentiometer smooths a wobbly supply. (a) False (b) True
14. 14.🔺 In the V-I-R triangle, how do we find R? (a) R = V × I (b) R = V + I (c) R = V ÷ I (d) R = I ÷ V
15. 15.🔺 A current of 10 mA flows when 2.2 V is joined across a resistor. What is its resistance (in ohms)?
16. 16.💡 A red LED uses 2 V and should get 25 mA. It runs from a 5 V supply. What resistor (in ohms) is needed in series?
17. 17.📏 Which unit measures the push of a cell? (a) ohm (Ω) (b) watt (W) (c) volt (V) (d) ampere (A)
18. 18.True or false: on an LED, the shorter leg is the cathode (−). (a) False (b) True
19. 19.True or false: a resistor has coloured bands. (a) False (b) True
20. 20.🔺 A current of 20 mA flows through a 100 Ω resistor. What is the voltage across it (in volts)? =
21. 21.⚡ A device works on 24 V and takes 3 A. What is its power (in watts)? =
22. 22.🔺 A current of 20 mA flows through a 400 Ω resistor. What is the voltage across it (in volts)? =
23. 23.💡 An LED is joined to a 6 V battery with no resistor; the leg next to the flat edge of its rim goes to the − side. What happens? (a) lights up (b) does not light (c) may burn out
24. 24.Which of these wastes electricity? (a) leave the TV on standby (b) use LED lamps (c) unplug idle chargers (d) set the AC to 24 °C
25. 25.True or false: the ammeter measures current. (a) False (b) True
26. 26.🧮 A 0.5 V battery is joined to 3 Ω and 2 Ω resistors in series. What current flows (in amperes)? =
27. 27.What does an LED do? (a) glows using little power (b) stores a little charge (c) beeps for an alarm (d) senses how bright it is
28. 28.🧩 Which component lets current go one way? (a) buzzer (b) transistor (c) potentiometer (d) diode
29. 29.🌈 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
30. 30.🔺 A current of 1.5 A flows through a 3 Ω resistor. What is the voltage across it (in volts)? =
31. 31.📏 How many watts (W) is 4.7 kW?
32. 32.🧾 A 2000 W appliance runs for 6 hours. How many units (kWh) of electricity does it use? =
33. 33.🧾 A 200 W appliance runs for 5 hours. How many units (kWh) of electricity does it use? =
34. 34.True or false: on an LED, the leg by the flat edge is the cathode (−). (a) False (b) True
35. 35.🧮 Two resistors in parallel give a total that is … (a) their sum (b) less than either one (c) more than either one (d) always zero
36. 36.💡 What does LED stand for? (a) large electric dial (b) light energy dial (c) low energy device (d) light-emitting diode
37. 37.🧮 Two equal 100 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
38. 38.🌈 A gold fourth band on a resistor means the value may be off by … (a) 50 % (b) 0 % (c) 25 % (d) 5 %
39. 39.Which of these saves electricity? (a) use old filament bulbs (b) leave fridge door open (c) run fans in empty rooms (d) close the fridge quickly
40. 40.📏 How many watts (W) is 4.8 kW?

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