Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 717 · 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 12 V supply is joined across a 4 Ω resistor. What current flows (in amperes)? =
2. 2.🧮 Two equal 40 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
3. 3.🔺 A current of 1.5 A flows through a 5 Ω resistor. What is the voltage across it (in volts)? =
4. 4.True or false: on an LED, the leg by the flat edge is the anode (+). (a) True (b) False
5. 5.🧮 Resistors of 330 Ω, 22 Ω, 10 Ω and 47 Ω are joined in series. What is the total resistance (in ohms)?
6. 6.True or false: a resistor has coloured bands. (a) False (b) True
7. 7.⚡ Power tells us … (a) the size of a cell (b) the length of a wire (c) energy used each second (d) the colour of light
8. 8.🌈 A gold fourth band on a resistor means the value may be off by … (a) 0 % (b) 5 % (c) 25 % (d) 50 %
9. 9.🌈 In the resistor colour code, which number does grey stand for?
10. 10.📏 How many ohms make 1 kilo-ohm (kΩ)? (a) 100 (b) 10 (c) 1000 (d) 1024
11. 11.🧩 Which part changes electrical energy into sound? (a) a capacitor (b) a buzzer (c) a resistor (d) a diode
12. 12.⚡ Which formula gives electric power? (a) P = V + I (b) P = I ÷ V (c) P = V ÷ I (d) P = V × I
13. 13.🔺 A current of 0.2 A flows through a 20 Ω resistor. What is the voltage across it (in volts)? =
14. 14.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) gets smaller (b) stays the same (c) becomes zero (d) gets bigger
15. 15.🧮 Five equal 250 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
16. 16.True or false: to use old filament bulbs saves electricity. (a) True (b) False
17. 17.📏 How many watts (W) is 0.9 kW?
18. 18.🌈 A resistor has the colour bands yellow, grey, brown. What is its value (in ohms)?
19. 19.🔺 A 2.5 V supply is joined across a 100 Ω resistor. What current flows (in milliamperes, mA)?
20. 20.🔺 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
21. 21.💡 Why does an LED need a resistor in series? (a) to store charge (b) to make it brighter (c) to limit the current (d) to change its colour
22. 22.🧮 Adding another resistor in series makes the total resistance … (a) stay the same (b) smaller (c) bigger (d) zero
23. 23.True or false: on an LED, the shorter leg is the anode (+). (a) True (b) False
24. 24.🧮 Resistors of 47 Ω and 100 Ω are joined in series. What is the total resistance (in ohms)?
25. 25.True or false: energy used each second is measured in watts (W). (a) False (b) True
26. 26.🧩 Which component glows using little power? (a) transistor (b) LED (c) resistor (d) thermistor
27. 27.True or false: on an LED, the longer leg is the cathode (−). (a) False (b) True
28. 28.🔺 A current of 1 A flows when 15 V is joined across a resistor. What is its resistance (in ohms)?
29. 29.📏 How many watts (W) is 2 kW?
30. 30.🔺 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
31. 31.⚡ A 0.9 W device works on 9 V. What current does it take (in amperes)? =
32. 32.🔺 A current of 25 mA flows through a 300 Ω resistor. What is the voltage across it (in volts)? =
33. 33.🔺 A 2.4 V supply is joined across a 12 Ω resistor. What current flows (in amperes)? =
34. 34.🧩 Which component senses how hot it is? (a) diode (b) resistor (c) LDR (d) thermistor
35. 35.💡 A red LED uses 2 V and should get 20 mA. It runs from a 6 V supply. What resistor (in ohms) is needed in series?
36. 36.🧮 Resistors of 220 Ω, 220 Ω and 20 Ω are joined in series. What is the total resistance (in ohms)?
37. 37.📏 Which unit measures power? (a) watt (W) (b) ampere (A) (c) volt (V) (d) ohm (Ω)
38. 38.🔺 A current of 25 mA flows through a 250 Ω resistor. What is the voltage across it (in volts)? =
39. 39.True or false: current is measured in ohms (Ω). (a) False (b) True
40. 40.⚡ A 0.6 W device works on 6 V. What current does it take (in amperes)? =

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