Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 986 · 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.True or false: the voltmeter is joined in series. (a) False (b) True
2. 2.⚡ Which formula gives electric power? (a) P = V ÷ I (b) P = V × I (c) P = I ÷ V (d) P = V + I
3. 3.🔺 A 13.2 V supply is joined across a 330 Ω resistor. What current flows (in milliamperes, mA)?
4. 4.🔺 A 3 V supply is joined across a 6 Ω resistor. What current flows (in amperes)? =
5. 5.🔍 Which is the odd one out? (a) unplug idle chargers (b) leave fridge door open (c) use old filament bulbs (d) leave the TV on standby
6. 6.🌈 A gold fourth band on a resistor means the value may be off by … (a) 50 % (b) 25 % (c) 5 % (d) 0 %
7. 7.🔺 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
8. 8.Which of these is measured in watts (W)? (a) energy used each second (b) resistance (c) voltage (d) current
9. 9.🔺 A current of 40 mA flows through a 400 Ω resistor. What is the voltage across it (in volts)? =
10. 10.🧮 Adding another resistor in series makes the total resistance … (a) zero (b) stay the same (c) bigger (d) smaller
11. 11.🧾 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
12. 12.⚡ Power tells us … (a) the colour of light (b) the size of a cell (c) energy used each second (d) the length of a wire
13. 13.🌈 Which band is read first on a resistor? (a) any band (b) the gold band (c) the one nearest an end (d) the widest gap
14. 14.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) becomes zero (b) stays the same (c) gets bigger (d) gets smaller
15. 15.💡 Why does an LED need a resistor in series? (a) to make it brighter (b) to change its colour (c) to store charge (d) to limit the current
16. 16.🌈 A resistor has the colour bands grey, yellow, yellow. What is its value in kilo-ohms (kΩ)? =
17. 17.🧮 Two resistors in parallel give a total that is … (a) always zero (b) their sum (c) less than either one (d) more than either one
18. 18.True or false: to use daylight to read wastes electricity. (a) False (b) True
19. 19.💡 On an LED, is the longer leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
20. 20.🧩 Which component is a resistance knob? (a) buzzer (b) potentiometer (c) LDR (d) thermistor
21. 21.True or false: the ammeter measures current. (a) False (b) True
22. 22.🔺 A current of 10 mA flows through a 500 Ω resistor. What is the voltage across it (in volts)? =
23. 23.True or false: energy used each second is measured in volts (V). (a) False (b) True
24. 24.📏 How many kilo-ohms (kΩ) is 3400 Ω? =
25. 25.🔺 A 10 V supply is joined across a 250 Ω resistor. What current flows (in milliamperes, mA)?
26. 26.🧩 Which component stores a little charge? (a) buzzer (b) diode (c) capacitor (d) resistor
27. 27.📏 How many milliamperes (mA) is 1.47 A?
28. 28.🧾 A 1000 W appliance runs for 10 hours. How many units (kWh) of electricity does it use? =
29. 29.🔺 A current of 0.2 A flows through a 10 Ω resistor. What is the voltage across it (in volts)? =
30. 30.🔺 A 20 V supply is joined across a 400 Ω resistor. What current flows (in milliamperes, mA)?
31. 31.True or false: how much a part resists is measured in volts (V). (a) True (b) False
32. 32.💡 A red LED (it uses 2 V) is joined with a 150 Ω resistor to a 2.75 V supply. What current flows (in mA)?
33. 33.🔺 In the V-I-R triangle, how do we find I? (a) I = V × R (b) I = V ÷ R (c) I = R ÷ V (d) I = V + R
34. 34.🧮 A 220 Ω resistor is joined in series with two equal 100 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
35. 35.📏 Which unit measures energy used each second? (a) ampere (A) (b) watt (W) (c) ohm (Ω) (d) volt (V)
36. 36.🔍 Which is the odd one out? (a) use old filament bulbs (b) leave the TV on standby (c) switch off empty rooms (d) run fans in empty rooms
37. 37.💡 What happens if an LED is put in backwards? (a) it makes a sound (b) it changes colour (c) it does not light (d) it lights brighter
38. 38.💡 A red LED (it uses 2 V) is joined with a 100 Ω resistor to a 2.5 V supply. What current flows (in mA)?
39. 39.🔺 A current of 20 mA flows when 2.4 V is joined across a resistor. What is its resistance (in ohms)?
40. 40.What does an LDR do? (a) is a resistance knob (b) boosts a small signal (c) senses how bright it is (d) stores a little charge

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