Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 889 · 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 of these is measured in ohms (Ω)? (a) energy used each second (b) power (c) how much a part resists (d) current
2. 2.True or false: a fuse makes a beeping sound. (a) True (b) False
3. 3.🔺 A current of 0.1 A flows through a 4 Ω resistor. What is the voltage across it (in volts)? =
4. 4.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 240 Ω resistor? (a) red-yellow-black (b) yellow-red-brown (c) red-yellow-red (d) red-yellow-brown
5. 5.Which of these is measured in ohms (Ω)? (a) the flow of charge (b) power (c) current (d) resistance
6. 6.What does a buzzer do? (a) glows using little power (b) beeps for an alarm (c) limits the current (d) stores a little charge
7. 7.🧩 Which component beeps for an alarm? (a) resistor (b) capacitor (c) buzzer (d) LED
8. 8.💡 What happens if an LED is put in backwards? (a) it does not light (b) it lights brighter (c) it changes colour (d) it makes a sound
9. 9.What does a transistor do? (a) boosts a small signal (b) makes a beeping sound (c) limits the current (d) blows if current is high
10. 10.💡 An LED is joined to a 3 V battery through a 1000 Ω resistor; the leg next to the flat edge of its rim goes to the + side. What happens? (a) lights up (b) may burn out (c) does not light
11. 11.🌈 A resistor has the colour bands violet, yellow, brown. What is its value (in ohms)?
12. 12.🧩 A capacitor in a circuit can … (a) store charge briefly (b) make light (c) spin a wheel (d) measure heat
13. 13.💡 An LED is joined to a 6 V battery with no 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
14. 14.💡 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) may burn out (b) does not light (c) lights up
15. 15.Which of these is measured in watts (W)? (a) the flow of charge (b) voltage (c) energy used each second (d) current
16. 16.🧩 Which component has coloured bands? (a) diode (b) capacitor (c) buzzer (d) resistor
17. 17.🔺 In the V-I-R triangle, how do we find V? (a) V = I ÷ R (b) V = I × R (c) V = R ÷ I (d) V = I + R
18. 18.⚡ A home appliance on the 230 V mains takes 5 A. What is its power (in watts)?
19. 19.💡 On an LED, is the leg by the flat edge the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
20. 20.🔺 A current of 0.25 A flows when 0.75 V is joined across a resistor. What is its resistance (in ohms)?
21. 21.🌈 A gold fourth band on a resistor means the value may be off by … (a) 5 % (b) 25 % (c) 0 % (d) 50 %
22. 22.🧮 Five equal 25 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
23. 23.🌈 A resistor has the colour bands brown, yellow, orange. What is its value (in ohms)?
24. 24.🔺 A current of 1 A flows through a 4 Ω resistor. What is the voltage across it (in volts)? =
25. 25.True or false: a fuse blows if current is high. (a) True (b) False
26. 26.⚡ A home appliance on the 230 V mains takes 10 A. What is its power (in watts)?
27. 27.📏 Which unit measures how much a part resists? (a) volt (V) (b) watt (W) (c) ohm (Ω) (d) ampere (A)
28. 28.🔺 A 16.5 V supply is joined across a 330 Ω resistor. What current flows (in milliamperes, mA)?
29. 29.Which of these wastes electricity? (a) switch off empty rooms (b) close the fridge quickly (c) unplug idle chargers (d) leave the TV on standby
30. 30.🔺 A current of 50 mA flows when 15 V is joined across a resistor. What is its resistance (in ohms)?
31. 31.🧩 Which component limits the current? (a) resistor (b) fuse (c) diode (d) motor
32. 32.🧮 Two equal 100 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
33. 33.📏 In the water-pipe picture of a circuit, voltage is like … (a) the pipe colour (b) the water tank lid (c) the tap handle (d) the water pressure
34. 34.📏 In the water-pipe picture of a circuit, current is like … (a) the water pressure (b) the pipe colour (c) the flow of water (d) a narrow pipe
35. 35.💡 An LED is joined to a 12 V battery with no resistor; the leg next to the flat edge of its rim goes to the − side. What happens? (a) lights up (b) may burn out (c) does not light
36. 36.🔺 In the V-I-R triangle, how do we find R? (a) R = V + I (b) R = V × I (c) R = V ÷ I (d) R = I ÷ V
37. 37.🔺 A current of 1 A flows when 4 V is joined across a resistor. What is its resistance (in ohms)?
38. 38.🧾 A 250 W appliance runs for 2 hours. How many units (kWh) of electricity does it use? =
39. 39.⚡ A home appliance on the 230 V mains takes 2 A. What is its power (in watts)?
40. 40.What does a fuse do? (a) lets current go one way (b) blows if current is high (c) turns a fan or wheels (d) is a resistance knob

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