Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 321 · 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.🧮 Adding another resistor in series makes the total resistance … (a) stay the same (b) bigger (c) smaller (d) zero
2. 2.🧮 Two equal 100 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
3. 3.📏 In the water-pipe picture of a circuit, current is like … (a) the pipe colour (b) the flow of water (c) a narrow pipe (d) the water pressure
4. 4.💡 On an LED, is the round-side leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
5. 5.🧮 Resistors of 10 Ω, 68 Ω, 47 Ω and 50 Ω are joined in series. What is the total resistance (in ohms)?
6. 6.True or false: to set the AC to 24 °C saves electricity. (a) False (b) True
7. 7.⚡ Power tells us … (a) energy used each second (b) the size of a cell (c) the length of a wire (d) the colour of light
8. 8.⚡ A 1.8 W device works on 9 V. What current does it take (in amperes)? =
9. 9.🧩 Which part changes electrical energy into movement? (a) a resistor (b) a motor (c) a fuse (d) an LED
10. 10.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 52 Ω resistor? (a) green-red-brown (b) red-green-black (c) blue-red-black (d) green-red-black
11. 11.📏 How many kilowatts (kW) is 2950 W? =
12. 12.💡 A red LED uses 2 V and should get 10 mA. It runs from a 6 V supply. What resistor (in ohms) is needed in series?
13. 13.💡 What does LED stand for? (a) low energy device (b) large electric dial (c) light-emitting diode (d) light energy dial
14. 14.⚡ Which formula gives electric power? (a) P = I ÷ V (b) P = V + I (c) P = V ÷ I (d) P = V × I
15. 15.🧩 Which component is a resistance knob? (a) transistor (b) motor (c) potentiometer (d) buzzer
16. 16.🧾 A family uses 160 units of electricity in a month and each unit costs ₹6. What is the bill (in ₹)?
17. 17.💡 What happens if an LED is put in backwards? (a) it makes a sound (b) it changes colour (c) it does not light (d) it lights brighter
18. 18.📏 Voltmeter or ammeter: which one is joined across a part? (a) ammeter (b) voltmeter
19. 19.What does a capacitor do? (a) turns a fan or wheels (b) is a resistance knob (c) smooths a wobbly supply (d) senses how bright it is
20. 20.🔺 A current of 40 mA flows through a 330 Ω resistor. What is the voltage across it (in volts)? =
21. 21.True or false: the voltmeter measures current. (a) True (b) False
22. 22.🔺 In the V-I-R triangle, how do we find R? (a) R = V × I (b) R = V + I (c) R = I ÷ V (d) R = V ÷ I
23. 23.🧮 Resistors of 150 Ω, 220 Ω and 50 Ω are joined in series. What is the total resistance (in ohms)?
24. 24.🧮 A 10 V battery is joined to 12 Ω and 8 Ω resistors in series. What current flows (in amperes)? =
25. 25.True or false: a thermistor senses how bright it is. (a) True (b) False
26. 26.🧩 Which component blows if current is high? (a) potentiometer (b) buzzer (c) fuse (d) capacitor
27. 27.🔺 A current of 1.5 A flows when 30 V is joined across a resistor. What is its resistance (in ohms)?
28. 28.True or false: on an LED, the round-side leg is the anode (+). (a) False (b) True
29. 29.🌈 A resistor has the colour bands green, violet, yellow. What is its value in kilo-ohms (kΩ)? =
30. 30.💡 An LED is joined to a 5 V battery through a 220 Ω resistor; the leg next to the flat edge of its rim goes to the − side. What happens? (a) does not light (b) may burn out (c) lights up
31. 31.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) becomes zero (b) gets bigger (c) gets smaller (d) stays the same
32. 32.Which of these is measured in volts (V)? (a) current (b) the push of a cell (c) the flow of charge (d) power
33. 33.🔺 A current of 20 mA flows when 3 V is joined across a resistor. What is its resistance (in ohms)?
34. 34.📏 How many watts (W) is 0.9 kW?
35. 35.🔺 A 0.75 V supply is joined across a 3 Ω resistor. What current flows (in amperes)? =
36. 36.⚡ A home appliance on the 230 V mains takes 1.5 A. What is its power (in watts)?
37. 37.🔺 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
38. 38.🔺 A current of 3 A flows through a 15 Ω resistor. What is the voltage across it (in volts)? =
39. 39.🧮 Two resistors in parallel give a total that is … (a) always zero (b) their sum (c) more than either one (d) less than either one
40. 40.🌈 In the resistor colour code, which number does white stand for?

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