Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 750 · 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 band is read first on a resistor? (a) the gold band (b) the widest gap (c) any band (d) the one nearest an end
2. 2.🔺 A 1.5 V supply is joined across a 6 Ω resistor. What current flows (in amperes)? =
3. 3.🔺 A current of 0.5 A flows through a 6 Ω resistor. What is the voltage across it (in volts)? =
4. 4.🧮 Four equal 80 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
5. 5.🌈 A resistor has the colour bands red, black, orange. What is its value in kilo-ohms (kΩ)? =
6. 6.Which of these is measured in volts (V)? (a) the push of a cell (b) how much a part resists (c) power (d) energy used each second
7. 7.🧮 A 220 Ω resistor is joined in series with two equal 20 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
8. 8.🔺 A current of 50 mA flows through a 220 Ω resistor. What is the voltage across it (in volts)? =
9. 9.🔍 Which is the odd one out? (a) unplug idle chargers (b) close the fridge quickly (c) switch off empty rooms (d) iron one shirt at a time
10. 10.⚡ A device works on 5 V and takes 2 A. What is its power (in watts)? =
11. 11.True or false: the ammeter measures current. (a) False (b) True
12. 12.🔺 A 9 V supply is joined across a 3 Ω resistor. What current flows (in amperes)? =
13. 13.🔺 A current of 1 A flows through a 20 Ω resistor. What is the voltage across it (in volts)? =
14. 14.What does a fuse do? (a) boosts a small signal (b) is a resistance knob (c) limits the current (d) blows if current is high
15. 15.🔺 A current of 3 A flows through an 8 Ω resistor. What is the voltage across it (in volts)? =
16. 16.True or false: a capacitor stores a little charge. (a) False (b) True
17. 17.True or false: how much a part resists is measured in volts (V). (a) True (b) False
18. 18.🧾 A 100 W filament bulb is swapped for a 15 W LED lamp that gives about the same light. Both would run for 1 hour. How many watt-hours (Wh) are saved?
19. 19.💡 An LED is joined to a 6 V battery through a 470 Ω resistor; the leg next to the flat edge of its rim goes to the − side. What happens? (a) may burn out (b) does not light (c) lights up
20. 20.📏 Which unit measures how much a part resists? (a) ohm (Ω) (b) volt (V) (c) watt (W) (d) ampere (A)
21. 21.🧮 A 470 Ω resistor is joined in series with two equal 50 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
22. 22.True or false: current is measured in amperes (A). (a) True (b) False
23. 23.💡 What happens if an LED is put in backwards? (a) it changes colour (b) it lights brighter (c) it does not light (d) it makes a sound
24. 24.What does a buzzer do? (a) beeps for an alarm (b) turns a fan or wheels (c) blows if current is high (d) smooths a wobbly supply
25. 25.🌈 A gold fourth band on a resistor means the value may be off by … (a) 0 % (b) 50 % (c) 25 % (d) 5 %
26. 26.📏 Which unit measures voltage? (a) watt (W) (b) ampere (A) (c) ohm (Ω) (d) volt (V)
27. 27.🧩 Which component senses how hot it is? (a) LDR (b) thermistor (c) diode (d) capacitor
28. 28.True or false: to unplug idle chargers wastes electricity. (a) False (b) True
29. 29.📏 Voltmeter or ammeter: which one is joined in series? (a) ammeter (b) voltmeter
30. 30.🧮 Resistors of 220 Ω, 33 Ω, 68 Ω and 330 Ω are joined in series. What is the total resistance (in ohms)?
31. 31.Which of these is measured in ohms (Ω)? (a) how much a part resists (b) energy used each second (c) the flow of charge (d) power
32. 32.🧮 Two resistors in parallel give a total that is … (a) less than either one (b) always zero (c) more than either one (d) their sum
33. 33.🧮 Two equal 10 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
34. 34.⚡ A device works on 3 V and takes 0.1 A. What is its power (in watts)? =
35. 35.💡 Does it save or waste electricity to switch off empty rooms? (a) saves electricity (b) wastes electricity
36. 36.📏 How many milliamperes (mA) is 2.33 A?
37. 37.🔺 A 6 V supply is joined across a 120 Ω resistor. What current flows (in milliamperes, mA)?
38. 38.🧩 Which part changes electrical energy into movement? (a) a resistor (b) an LED (c) a fuse (d) a motor
39. 39.🔺 A current of 20 mA flows through a 120 Ω resistor. What is the voltage across it (in volts)? =
40. 40.🧮 Two equal 40 Ω resistors are joined in parallel. What is the total resistance (in ohms)?

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