Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 828 · 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 12.5 V supply is joined across a 5 Ω resistor. What current flows (in amperes)? =
2. 2.🔺 A 6 V supply is joined across a 12 Ω resistor. What current flows (in amperes)? =
3. 3.🧾 A 1500 W appliance runs for 4 hours. How many units (kWh) of electricity does it use? =
4. 4.True or false: on an LED, the round-side leg is the cathode (−). (a) False (b) True
5. 5.🧩 Which component has coloured bands? (a) resistor (b) capacitor (c) diode (d) fuse
6. 6.🧩 Which part changes electrical energy into sound? (a) a buzzer (b) a resistor (c) a diode (d) a capacitor
7. 7.⚡ Power tells us … (a) the length of a wire (b) energy used each second (c) the size of a cell (d) the colour of light
8. 8.True or false: the flow of charge is measured in watts (W). (a) True (b) False
9. 9.🌈 A resistor has the colour bands violet, white, black. What is its value (in ohms)?
10. 10.True or false: on an LED, the shorter leg is the cathode (−). (a) True (b) False
11. 11.🔍 Which is the odd one out? (a) leave the TV on standby (b) use LED lamps (c) use old filament bulbs (d) leave fridge door open
12. 12.🔺 A current of 10 mA flows through a 470 Ω resistor. What is the voltage across it (in volts)? =
13. 13.💡 Why does an LED need a resistor in series? (a) to limit the current (b) to change its colour (c) to make it brighter (d) to store charge
14. 14.🧮 Four equal 400 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
15. 15.🔺 A current of 0.25 A flows through a 5 Ω resistor. What is the voltage across it (in volts)? =
16. 16.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) gets bigger (b) becomes zero (c) stays the same (d) gets smaller
17. 17.Which of these is measured in volts (V)? (a) current (b) resistance (c) power (d) the push of a cell
18. 18.🔺 A current of 0.25 A flows through a 3 Ω resistor. What is the voltage across it (in volts)? =
19. 19.🧮 Two resistors in parallel give a total that is … (a) less than either one (b) more than either one (c) their sum (d) always zero
20. 20.💡 A red LED (it uses 2 V) is joined with a 200 Ω resistor to a 3 V supply. What current flows (in mA)?
21. 21.⚡ A 9 W device works on 9 V. What current does it take (in amperes)? =
22. 22.🔺 In the V-I-R triangle, how do we find I? (a) I = V × R (b) I = R ÷ V (c) I = V + R (d) I = V ÷ R
23. 23.🌈 A resistor has the colour bands orange, green, red. What is its value (in ohms)?
24. 24.🧮 Three equal 300 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
25. 25.🌈 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
26. 26.🔺 A current of 50 mA flows through a 200 Ω resistor. What is the voltage across it (in volts)? =
27. 27.📏 Which unit measures current? (a) watt (W) (b) ohm (Ω) (c) ampere (A) (d) volt (V)
28. 28.⚡ A home appliance on the 230 V mains takes 0.5 A. What is its power (in watts)?
29. 29.🧮 Resistors of 220 Ω, 68 Ω and 47 Ω are joined in series. What is the total resistance (in ohms)?
30. 30.⚡ A device works on 9 V and takes 1.5 A. What is its power (in watts)? =
31. 31.⚡ A device works on 6 V and takes 3 A. What is its power (in watts)? =
32. 32.🔺 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
33. 33.True or false: an LDR senses how hot it is. (a) False (b) True
34. 34.🔺 A current of 0.2 A flows when 2.4 V is joined across a resistor. What is its resistance (in ohms)?
35. 35.🔺 A current of 25 mA flows through a 300 Ω resistor. What is the voltage across it (in volts)? =
36. 36.True or false: on an LED, the longer leg is the anode (+). (a) True (b) False
37. 37.🔺 A current of 25 mA flows when 12.5 V is joined across a resistor. What is its resistance (in ohms)?
38. 38.🧩 Which component senses how bright it is? (a) LDR (b) capacitor (c) transistor (d) thermistor
39. 39.💡 Does it save or waste electricity to close the fridge quickly? (a) wastes electricity (b) saves electricity
40. 40.💡 An LED is joined to a 5 V battery with no resistor; its long leg goes to the + side and its short leg to the − side. What happens? (a) may burn out (b) does not light (c) lights up

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