Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 517 · 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.📏 Voltmeter or ammeter: which one is joined in series? (a) ammeter (b) voltmeter
2. 2.🔺 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
3. 3.Which of these is measured in ohms (Ω)? (a) energy used each second (b) how much a part resists (c) the push of a cell (d) power
4. 4.🔍 Which is the odd one out? (a) set the AC to 24 °C (b) switch off empty rooms (c) close the fridge quickly (d) iron one shirt at a time
5. 5.💡 A blue LED uses 3 V and should get 25 mA. It runs from a 9 V supply. What resistor (in ohms) is needed in series?
6. 6.⚡ A home appliance on the 230 V mains takes 4 A. What is its power (in watts)?
7. 7.⚡ A 0.6 W device works on 6 V. What current does it take (in amperes)? =
8. 8.📏 Which unit measures the push of a cell? (a) ohm (Ω) (b) volt (V) (c) ampere (A) (d) watt (W)
9. 9.What does an LDR do? (a) smooths a wobbly supply (b) has coloured bands (c) senses how bright it is (d) is a resistance knob
10. 10.💡 On an LED, is the longer leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
11. 11.💡 An LED is joined to a 5 V battery through a 1000 Ω resistor; its long leg goes to the − side and its short leg to the + side. What happens? (a) does not light (b) may burn out (c) lights up
12. 12.💡 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?
13. 13.🧩 Which component turns a fan or wheels? (a) potentiometer (b) capacitor (c) motor (d) thermistor
14. 14.🧾 A family uses 110 units of electricity in a month and each unit costs ₹4. What is the bill (in ₹)?
15. 15.🧮 Resistors of 10 Ω, 22 Ω and 220 Ω are joined in series. What is the total resistance (in ohms)?
16. 16.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 60000 Ω resistor? (a) blue-black-yellow (b) blue-black-orange (c) blue-black-red (d) violet-blue-orange
17. 17.⚡ A 36 W device works on 24 V. What current does it take (in amperes)? =
18. 18.🔺 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
19. 19.True or false: on an LED, the leg by the flat edge is the anode (+). (a) True (b) False
20. 20.🔺 A 1.5 V supply is joined across a 150 Ω resistor. What current flows (in milliamperes, mA)?
21. 21.🔍 Which is the odd one out? (a) unplug idle chargers (b) leave the TV on standby (c) use daylight to read (d) close the fridge quickly
22. 22.🔺 A current of 2 A flows through a 4 Ω resistor. What is the voltage across it (in volts)? =
23. 23.⚡ Which formula gives electric power? (a) P = V + I (b) P = I ÷ V (c) P = V × I (d) P = V ÷ I
24. 24.🧮 Two resistors in parallel give a total that is … (a) more than either one (b) always zero (c) less than either one (d) their sum
25. 25.🧮 Resistors of 100 Ω, 100 Ω and 330 Ω are joined in series. What is the total resistance (in ohms)?
26. 26.🔺 A current of 2 A flows when 40 V is joined across a resistor. What is its resistance (in ohms)?
27. 27.🌈 A resistor has the colour bands white, black, brown. What is its value (in ohms)?
28. 28.🔺 A current of 0.25 A flows through a 5 Ω resistor. What is the voltage across it (in volts)? =
29. 29.🔺 A current of 2 A flows through a 12 Ω resistor. What is the voltage across it (in volts)? =
30. 30.🧾 Which lamp gives the same light for the least power? (a) an LED lamp (b) a candle (c) an oil lamp (d) a filament bulb
31. 31.🌈 A gold fourth band on a resistor means the value may be off by … (a) 0 % (b) 5 % (c) 50 % (d) 25 %
32. 32.📏 How many kilowatts (kW) is 4350 W? =
33. 33.True or false: the ammeter measures voltage. (a) True (b) False
34. 34.⚡ A device works on 5 V and takes 0.25 A. What is its power (in watts)? =
35. 35.🧮 Four equal 40 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
36. 36.⚡ 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
37. 37.🧩 Which part changes electrical energy into sound? (a) a capacitor (b) a diode (c) a resistor (d) a buzzer
38. 38.True or false: energy used each second is measured in amperes (A). (a) True (b) False
39. 39.What does a buzzer do? (a) senses how hot it is (b) glows using little power (c) smooths a wobbly supply (d) beeps for an alarm
40. 40.🔺 A current of 2.5 A flows through an 8 Ω resistor. What is the voltage across it (in volts)? =

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