Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 161 · 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.What does a diode do? (a) has coloured bands (b) lets current go one way (c) beeps for an alarm (d) senses how bright it is
2. 2.🔺 A current of 50 mA flows through a 400 Ω resistor. What is the voltage across it (in volts)? =
3. 3.📏 Which unit measures voltage? (a) volt (V) (b) watt (W) (c) ampere (A) (d) ohm (Ω)
4. 4.🌈 In the resistor colour code, which number does yellow stand for?
5. 5.True or false: on an LED, the leg by the flat edge is the cathode (−). (a) False (b) True
6. 6.Which of these is measured in volts (V)? (a) the flow of charge (b) voltage (c) how much a part resists (d) current
7. 7.True or false: on an LED, the shorter leg is the cathode (−). (a) False (b) True
8. 8.📏 Voltmeter or ammeter: which one is joined in series? (a) ammeter (b) voltmeter
9. 9.🧾 A 40 W filament bulb is swapped for a 6 W LED lamp that gives about the same light. Both would run for 6 hours. How many watt-hours (Wh) are saved?
10. 10.🧮 Two resistors in parallel give a total that is … (a) less than either one (b) more than either one (c) their sum (d) always zero
11. 11.🔺 A current of 0.1 A flows through a 6 Ω resistor. What is the voltage across it (in volts)? =
12. 12.Which of these is measured in ohms (Ω)? (a) power (b) how much a part resists (c) the flow of charge (d) energy used each second
13. 13.🧾 Which lamp gives the same light for the least power? (a) a filament bulb (b) a candle (c) an oil lamp (d) an LED lamp
14. 14.🔺 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
15. 15.🧮 Two equal 50 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
16. 16.🔺 A current of 1.5 A flows through a 6 Ω resistor. What is the voltage across it (in volts)? =
17. 17.🧮 A 1.4 V battery is joined to 12 Ω and 2 Ω resistors in series. What current flows (in amperes)? =
18. 18.🔺 A 24 V supply is joined across a 12 Ω resistor. What current flows (in amperes)? =
19. 19.💡 Does it save or waste electricity to switch off empty rooms? (a) wastes electricity (b) saves electricity
20. 20.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) gets smaller (b) gets bigger (c) stays the same (d) becomes zero
21. 21.🔺 A current of 0.25 A flows when 0.75 V is joined across a resistor. What is its resistance (in ohms)?
22. 22.📏 How many milliamperes (mA) is 0.89 A?
23. 23.🔺 A current of 10 mA flows through a 220 Ω resistor. What is the voltage across it (in volts)? =
24. 24.📏 Voltmeter or ammeter: which one measures current? (a) voltmeter (b) ammeter
25. 25.🔺 A current of 20 mA flows through a 470 Ω resistor. What is the voltage across it (in volts)? =
26. 26.📏 Which unit measures power? (a) watt (W) (b) ohm (Ω) (c) ampere (A) (d) volt (V)
27. 27.🔺 In the V-I-R triangle, how do we find I? (a) I = R ÷ V (b) I = V × R (c) I = V + R (d) I = V ÷ R
28. 28.Which of these is measured in ohms (Ω)? (a) energy used each second (b) current (c) power (d) resistance
29. 29.📏 How many kilowatts (kW) is 4450 W? =
30. 30.🧮 Three equal 300 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
31. 31.Which of these is measured in watts (W)? (a) how much a part resists (b) energy used each second (c) the push of a cell (d) current
32. 32.🧾 One “unit” on an electricity bill is … (a) 1 volt (b) 1 kilowatt-hour (kWh) (c) 1 ampere (d) 1 watt
33. 33.🌈 A resistor has the colour bands red, violet, black. What is its value (in ohms)?
34. 34.💡 Does it save or waste electricity to use daylight to read? (a) wastes electricity (b) saves electricity
35. 35.🔺 A current of 20 mA flows through a 200 Ω resistor. What is the voltage across it (in volts)? =
36. 36.🧮 A 2.75 V battery is joined to 3 Ω and 8 Ω resistors in series. What current flows (in amperes)? =
37. 37.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 3400 Ω resistor? (a) yellow-orange-red (b) orange-yellow-orange (c) orange-yellow-brown (d) orange-yellow-red
38. 38.🧮 Resistors of 10 Ω, 33 Ω, 220 Ω and 10 Ω are joined in series. What is the total resistance (in ohms)?
39. 39.🔺 A current of 0.25 A flows through a 10 Ω resistor. What is the voltage across it (in volts)? =
40. 40.What does a motor do? (a) smooths a wobbly supply (b) senses how hot it is (c) turns a fan or wheels (d) lets current go one way

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