Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 316 · 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.True or false: the ammeter measures voltage. (a) True (b) False
2. 2.🔺 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
3. 3.🔺 A current of 2.5 A flows through a 10 Ω resistor. What is the voltage across it (in volts)? =
4. 4.🔺 In the V-I-R triangle, how do we find R? (a) R = V × I (b) R = I ÷ V (c) R = V + I (d) R = V ÷ I
5. 5.🧮 Resistors of 47 Ω, 47 Ω and 68 Ω are joined in series. What is the total resistance (in ohms)?
6. 6.🔺 A current of 25 mA flows through a 100 Ω resistor. What is the voltage across it (in volts)? =
7. 7.⚡ A home appliance on the 230 V mains takes 8 A. What is its power (in watts)?
8. 8.🌈 Which band is read first on a resistor? (a) the widest gap (b) any band (c) the one nearest an end (d) the gold band
9. 9.🔺 A current of 1 A flows when 2 V is joined across a resistor. What is its resistance (in ohms)?
10. 10.📏 Voltmeter or ammeter: which one is joined across a part? (a) voltmeter (b) ammeter
11. 11.🧮 Five equal 125 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
12. 12.🧮 A 220 Ω resistor is joined in series with two equal 220 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
13. 13.🧮 Resistors of 20 Ω, 22 Ω and 100 Ω are joined in series. What is the total resistance (in ohms)?
14. 14.🧩 Which part changes electrical energy into sound? (a) a resistor (b) a capacitor (c) a diode (d) a buzzer
15. 15.Which of these is measured in watts (W)? (a) the flow of charge (b) the push of a cell (c) energy used each second (d) voltage
16. 16.⚡ Power tells us … (a) the size of a cell (b) energy used each second (c) the length of a wire (d) the colour of light
17. 17.🧮 Two equal 470 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
18. 18.🔺 A current of 40 mA flows through a 150 Ω resistor. What is the voltage across it (in volts)? =
19. 19.True or false: a capacitor blows if current is high. (a) True (b) False
20. 20.💡 On an LED, is the longer leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
21. 21.💡 Why does an LED need a resistor in series? (a) to make it brighter (b) to change its colour (c) to limit the current (d) to store charge
22. 22.True or false: on an LED, the round-side leg is the cathode (−). (a) False (b) True
23. 23.🌈 A resistor has the colour bands orange, grey, orange. What is its value (in ohms)?
24. 24.True or false: on an LED, the shorter leg is the anode (+). (a) False (b) True
25. 25.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) stays the same (b) gets smaller (c) gets bigger (d) becomes zero
26. 26.⚡ Which formula gives electric power? (a) P = V + I (b) P = V ÷ I (c) P = I ÷ V (d) P = V × I
27. 27.What does a capacitor do? (a) stores a little charge (b) is a resistance knob (c) senses how bright it is (d) glows using little power
28. 28.🔺 A 12 V supply is joined across a 300 Ω resistor. What current flows (in milliamperes, mA)?
29. 29.True or false: a resistor has coloured bands. (a) False (b) True
30. 30.What does a fuse do? (a) makes things spin (b) glows using little power (c) has coloured bands (d) blows if current is high
31. 31.📏 How many kilowatts (kW) is 3000 W? =
32. 32.🧩 Which component smooths a wobbly supply? (a) buzzer (b) motor (c) capacitor (d) LDR
33. 33.Which of these saves electricity? (a) iron one shirt at a time (b) leave fridge door open (c) unplug idle chargers (d) leave the TV on standby
34. 34.💡 What happens if an LED is put in backwards? (a) it changes colour (b) it makes a sound (c) it does not light (d) it lights brighter
35. 35.⚡ A home appliance on the 230 V mains takes 4 A. What is its power (in watts)?
36. 36.True or false: on an LED, the leg by the flat edge is the cathode (−). (a) True (b) False
37. 37.🧾 A family uses 20 units of electricity in a month and each unit costs ₹7. What is the bill (in ₹)?
38. 38.🧩 Which component glows using little power? (a) diode (b) LED (c) capacitor (d) transistor
39. 39.📏 In the water-pipe picture of a circuit, voltage is like … (a) the water tank lid (b) the pipe colour (c) the water pressure (d) the tap handle
40. 40.🔺 A current of 25 mA flows when 3.75 V is joined across a resistor. What is its resistance (in ohms)?

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