Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 42 · 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.Which of these is measured in volts (V)? (a) voltage (b) current (c) how much a part resists (d) energy used each second
2. 2.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 43 Ω resistor? (a) yellow-orange-black (b) orange-yellow-black (c) yellow-orange-brown (d) green-orange-black
3. 3.📏 Which unit measures resistance? (a) ohm (Ω) (b) volt (V) (c) watt (W) (d) ampere (A)
4. 4.🧮 Resistors of 33 Ω and 22 Ω are joined in series. What is the total resistance (in ohms)?
5. 5.🌈 A gold fourth band on a resistor means the value may be off by … (a) 5 % (b) 25 % (c) 0 % (d) 50 %
6. 6.📏 Voltmeter or ammeter: which one is joined across a part? (a) ammeter (b) voltmeter
7. 7.📏 Voltmeter or ammeter: which one measures current? (a) voltmeter (b) ammeter
8. 8.💡 An LED is joined to a 3 V battery through a 330 Ω resistor; the leg next to the flat edge of its rim goes to the − side. What happens? (a) may burn out (b) lights up (c) does not light
9. 9.🔺 A current of 20 mA flows through a 200 Ω resistor. What is the voltage across it (in volts)? =
10. 10.True or false: the voltmeter measures voltage. (a) False (b) True
11. 11.🧩 Which component glows using little power? (a) LDR (b) LED (c) capacitor (d) potentiometer
12. 12.🔺 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
13. 13.🧩 Which part changes electrical energy into sound? (a) a diode (b) a capacitor (c) a resistor (d) a buzzer
14. 14.⚡ A device works on 1.5 V and takes 0.2 A. What is its power (in watts)? =
15. 15.Which of these wastes electricity? (a) use LED lamps (b) use daylight to read (c) switch off empty rooms (d) leave the TV on standby
16. 16.Which of these wastes electricity? (a) set the AC to 24 °C (b) use LED lamps (c) leave fridge door open (d) use daylight to read
17. 17.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) gets smaller (b) gets bigger (c) becomes zero (d) stays the same
18. 18.True or false: energy used each second is measured in watts (W). (a) True (b) False
19. 19.🌈 A resistor has the colour bands violet, red, black. What is its value (in ohms)?
20. 20.🌈 A resistor has the colour bands brown, violet, red. What is its value in kilo-ohms (kΩ)? =
21. 21.🌈 A resistor has the colour bands red, black, black. What is its value (in ohms)?
22. 22.🔺 A 2 V supply is joined across a 20 Ω resistor. What current flows (in amperes)? =
23. 23.True or false: to use daylight to read saves electricity. (a) True (b) False
24. 24.🔺 In the V-I-R triangle, how do we find V? (a) V = I ÷ R (b) V = I × R (c) V = I + R (d) V = R ÷ I
25. 25.🧩 Which component turns a fan or wheels? (a) capacitor (b) motor (c) diode (d) fuse
26. 26.Which of these saves electricity? (a) iron one shirt at a time (b) set the AC to 24 °C (c) leave the TV on standby (d) use old filament bulbs
27. 27.🧾 A 50 W appliance runs for 5 hours. How many units (kWh) of electricity does it use? =
28. 28.⚡ A home appliance on the 230 V mains takes 1.5 A. What is its power (in watts)?
29. 29.⚡ A 4.5 W device works on 1.5 V. What current does it take (in amperes)? =
30. 30.💡 A blue LED uses 3 V and should get 10 mA. It runs from a 12 V supply. What resistor (in ohms) is needed in series?
31. 31.⚡ A device works on 9 V and takes 0.25 A. What is its power (in watts)? =
32. 32.💡 On an LED, is the leg by the flat edge the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
33. 33.True or false: voltage is measured in amperes (A). (a) False (b) True
34. 34.🔺 A current of 2.5 A flows through a 5 Ω resistor. What is the voltage across it (in volts)? =
35. 35.🔺 A current of 25 mA flows when 6.25 V is joined across a resistor. What is its resistance (in ohms)?
36. 36.Which of these is measured in watts (W)? (a) resistance (b) voltage (c) how much a part resists (d) power
37. 37.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 610 Ω resistor? (a) blue-brown-black (b) brown-blue-brown (c) blue-brown-red (d) blue-brown-brown
38. 38.🧮 Adding another resistor in series makes the total resistance … (a) smaller (b) zero (c) stay the same (d) bigger
39. 39.🧮 Two equal 220 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
40. 40.True or false: on an LED, the round-side leg is the anode (+). (a) False (b) True

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