Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 759 · 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.🧮 A 100 Ω resistor is joined in series with two equal 330 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
2. 2.🌈 A resistor has the colour bands brown, green, red. What is its value in kilo-ohms (kΩ)? =
3. 3.🧩 A capacitor in a circuit can … (a) spin a wheel (b) store charge briefly (c) measure heat (d) make light
4. 4.🧩 Which part changes electrical energy into sound? (a) a capacitor (b) a buzzer (c) a diode (d) a resistor
5. 5.🔺 An 11.75 V supply is joined across a 470 Ω resistor. What current flows (in milliamperes, mA)?
6. 6.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) stays the same (b) gets smaller (c) becomes zero (d) gets bigger
7. 7.🔺 A current of 0.2 A flows when 0.4 V is joined across a resistor. What is its resistance (in ohms)?
8. 8.Which of these is measured in watts (W)? (a) power (b) voltage (c) how much a part resists (d) current
9. 9.🌈 A gold fourth band on a resistor means the value may be off by … (a) 50 % (b) 25 % (c) 5 % (d) 0 %
10. 10.🧮 Resistors of 220 Ω, 330 Ω and 150 Ω are joined in series. What is the total resistance (in ohms)?
11. 11.🔺 A current of 2.5 A flows through an 8 Ω resistor. What is the voltage across it (in volts)? =
12. 12.📏 Voltmeter or ammeter: which one is joined in series? (a) voltmeter (b) ammeter
13. 13.🔍 Which is the odd one out? (a) leave fridge door open (b) run fans in empty rooms (c) use old filament bulbs (d) use daylight to read
14. 14.📏 How many watts (W) is 0.5 kW?
15. 15.What does a fuse do? (a) boosts a small signal (b) glows using little power (c) makes a beeping sound (d) blows if current is high
16. 16.🔺 A 20 V supply is joined across a 400 Ω resistor. What current flows (in milliamperes, mA)?
17. 17.📏 Which unit measures how much a part resists? (a) watt (W) (b) ampere (A) (c) ohm (Ω) (d) volt (V)
18. 18.📏 How many milliamperes (mA) is 1.8 A?
19. 19.🔍 Which is the odd one out? (a) set the AC to 24 °C (b) leave the TV on standby (c) close the fridge quickly (d) unplug idle chargers
20. 20.📏 How many kilo-ohms (kΩ) is 900 Ω? =
21. 21.True or false: to use LED lamps wastes electricity. (a) True (b) False
22. 22.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 3500 Ω resistor? (a) green-orange-red (b) orange-green-orange (c) orange-green-red (d) orange-green-brown
23. 23.🔺 A 5 V supply is joined across a 200 Ω resistor. What current flows (in milliamperes, mA)?
24. 24.🌈 Which band is read first on a resistor? (a) the widest gap (b) any band (c) the gold band (d) the one nearest an end
25. 25.📏 How many watts (W) is 1.8 kW?
26. 26.🔺 A current of 50 mA flows when 20 V is joined across a resistor. What is its resistance (in ohms)?
27. 27.⚡ A 0.3 W device works on 3 V. What current does it take (in amperes)? =
28. 28.True or false: current is measured in amperes (A). (a) False (b) True
29. 29.🧮 A 1.1 V battery is joined to 8 Ω and 3 Ω resistors in series. What current flows (in amperes)? =
30. 30.True or false: the voltmeter is joined in series. (a) False (b) True
31. 31.True or false: on an LED, the longer leg is the cathode (−). (a) True (b) False
32. 32.🧮 A 1 V battery is joined to 3 Ω and 2 Ω resistors in series. What current flows (in amperes)? =
33. 33.True or false: a potentiometer lets current go one way. (a) True (b) False
34. 34.🔺 A current of 3 A flows through a 4 Ω resistor. What is the voltage across it (in volts)? =
35. 35.🧩 Which component beeps for an alarm? (a) transistor (b) buzzer (c) potentiometer (d) fuse
36. 36.⚡ A device works on 5 V and takes 0.2 A. What is its power (in watts)? =
37. 37.🌈 A resistor has the colour bands brown, brown, orange. What is its value (in ohms)?
38. 38.💡 An LED is joined to a 6 V battery through a 470 Ω resistor; its long leg goes to the − side and its short leg to the + side. What happens? (a) lights up (b) may burn out (c) does not light
39. 39.⚡ A home appliance on the 230 V mains takes 4 A. What is its power (in watts)?
40. 40.🧩 Which component senses how bright it is? (a) LDR (b) resistor (c) transistor (d) motor

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