Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 393 · 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) the one nearest an end (d) any band
2. 2.⚡ A device works on 1.5 V and takes 1 A. What is its power (in watts)? =
3. 3.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) becomes zero (b) gets smaller (c) gets bigger (d) stays the same
4. 4.🔺 A current of 0.25 A flows through a 4 Ω resistor. What is the voltage across it (in volts)? =
5. 5.🔺 A current of 0.5 A flows through a 4 Ω resistor. What is the voltage across it (in volts)? =
6. 6.True or false: a resistor limits the current. (a) False (b) True
7. 7.💡 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) may burn out (b) does not light (c) lights up
8. 8.🔺 A current of 3 A flows through a 5 Ω resistor. What is the voltage across it (in volts)? =
9. 9.🧾 One “unit” on an electricity bill is … (a) 1 watt (b) 1 volt (c) 1 ampere (d) 1 kilowatt-hour (kWh)
10. 10.True or false: on an LED, the round-side leg is the cathode (−). (a) False (b) True
11. 11.⚡ A 0.75 W device works on 1.5 V. What current does it take (in amperes)? =
12. 12.🔺 A current of 2.5 A flows through a 10 Ω resistor. What is the voltage across it (in volts)? =
13. 13.True or false: the ammeter measures voltage. (a) True (b) False
14. 14.⚡ Power tells us … (a) the colour of light (b) energy used each second (c) the length of a wire (d) the size of a cell
15. 15.🔺 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
16. 16.🧮 Two resistors in parallel give a total that is … (a) their sum (b) more than either one (c) always zero (d) less than either one
17. 17.💡 A red LED (it uses 2 V) is joined with a 100 Ω resistor to a 4 V supply. What current flows (in mA)?
18. 18.🧮 Adding another resistor in series makes the total resistance … (a) bigger (b) smaller (c) zero (d) stay the same
19. 19.📏 Which unit measures power? (a) ampere (A) (b) ohm (Ω) (c) watt (W) (d) volt (V)
20. 20.🔺 A current of 10 mA flows when 2.5 V is joined across a resistor. What is its resistance (in ohms)?
21. 21.🔍 Which is the odd one out? (a) set the AC to 24 °C (b) close the fridge quickly (c) iron one shirt at a time (d) unplug idle chargers
22. 22.🔺 A current of 10 mA flows through a 220 Ω resistor. What is the voltage across it (in volts)? =
23. 23.🔺 A current of 50 mA flows when 16.5 V is joined across a resistor. What is its resistance (in ohms)?
24. 24.🌈 In the resistor colour code, which number does blue stand for?
25. 25.True or false: a diode makes a beeping sound. (a) True (b) False
26. 26.🧮 Two equal 20 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
27. 27.🌈 In the resistor colour code, which number does brown stand for?
28. 28.🔺 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
29. 29.🔍 Which is the odd one out? (a) run fans in empty rooms (b) leave fridge door open (c) set the AC to 24 °C (d) use old filament bulbs
30. 30.💡 Does it save or waste electricity to close the fridge quickly? (a) saves electricity (b) wastes electricity
31. 31.🔺 A current of 0.1 A flows when 1.5 V is joined across a resistor. What is its resistance (in ohms)?
32. 32.📏 Which unit measures the push of a cell? (a) ampere (A) (b) ohm (Ω) (c) watt (W) (d) volt (V)
33. 33.🌈 In the resistor colour code, which number does grey stand for?
34. 34.💡 A red LED (it uses 2 V) is joined with a 200 Ω resistor to a 4 V supply. What current flows (in mA)?
35. 35.🔺 A current of 3 A flows through a 10 Ω resistor. What is the voltage across it (in volts)? =
36. 36.⚡ Which formula gives electric power? (a) P = V ÷ I (b) P = V + I (c) P = I ÷ V (d) P = V × I
37. 37.What does a motor do? (a) makes a beeping sound (b) blows if current is high (c) senses how bright it is (d) turns a fan or wheels
38. 38.🧾 Which lamp gives the same light for the least power? (a) a candle (b) a filament bulb (c) an oil lamp (d) an LED lamp
39. 39.🔍 Which is the odd one out? (a) unplug idle chargers (b) run fans in empty rooms (c) set the AC to 24 °C (d) use LED lamps
40. 40.💡 On an LED, is the longer leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)

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