Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 363 · 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.🔺 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
2. 2.🔺 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
3. 3.📏 How many milliamperes (mA) is 0.45 A?
4. 4.⚡ A device works on 1.5 V and takes 1.5 A. What is its power (in watts)? =
5. 5.🧮 An 8 V battery is joined to 3 Ω and 5 Ω resistors in series. What current flows (in amperes)? =
6. 6.💡 A red LED (it uses 2 V) is joined with a 300 Ω resistor to a 6.5 V supply. What current flows (in mA)?
7. 7.🧮 Adding another resistor in series makes the total resistance … (a) bigger (b) smaller (c) stay the same (d) zero
8. 8.💡 On an LED, is the leg by the flat edge the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
9. 9.🔺 A current of 20 mA flows through a 470 Ω resistor. What is the voltage across it (in volts)? =
10. 10.🌈 A resistor has the colour bands blue, orange, orange. What is its value in kilo-ohms (kΩ)? =
11. 11.True or false: a resistor boosts a small signal. (a) False (b) True
12. 12.🧩 Which component senses how hot it is? (a) thermistor (b) LED (c) buzzer (d) fuse
13. 13.🔺 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
14. 14.⚡ Power tells us … (a) energy used each second (b) the size of a cell (c) the length of a wire (d) the colour of light
15. 15.🌈 A gold fourth band on a resistor means the value may be off by … (a) 0 % (b) 5 % (c) 50 % (d) 25 %
16. 16.🔺 A current of 0.2 A flows through a 12 Ω resistor. What is the voltage across it (in volts)? =
17. 17.📏 How many ohms (Ω) is 2 kΩ?
18. 18.🌈 A resistor has the colour bands white, black, black. What is its value (in ohms)?
19. 19.🧮 Resistors of 100 Ω, 100 Ω, 220 Ω and 50 Ω are joined in series. What is the total resistance (in ohms)?
20. 20.⚡ A home appliance on the 230 V mains takes 1.5 A. What is its power (in watts)?
21. 21.🔺 A current of 0.1 A flows through a 15 Ω resistor. What is the voltage across it (in volts)? =
22. 22.🔺 A 40 V supply is joined across a 20 Ω resistor. What current flows (in amperes)? =
23. 23.Which of these is measured in ohms (Ω)? (a) how much a part resists (b) voltage (c) the push of a cell (d) energy used each second
24. 24.🧮 Two equal 50 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
25. 25.🔺 A 3 V supply is joined across a 150 Ω resistor. What current flows (in milliamperes, mA)?
26. 26.What does an LED do? (a) glows using little power (b) blows if current is high (c) is a resistance knob (d) senses how hot it is
27. 27.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 48000 Ω resistor? (a) grey-yellow-orange (b) yellow-grey-yellow (c) yellow-grey-orange (d) yellow-grey-red
28. 28.True or false: a fuse blows if current is high. (a) True (b) False
29. 29.🔺 A current of 50 mA flows through a 300 Ω resistor. What is the voltage across it (in volts)? =
30. 30.What does a resistor do? (a) beeps for an alarm (b) stores a little charge (c) limits the current (d) makes a beeping sound
31. 31.🌈 A resistor has the colour bands orange, black, black. What is its value (in ohms)?
32. 32.🔺 A 10 V supply is joined across a 10 Ω resistor. What current flows (in amperes)? =
33. 33.⚡ Which formula gives electric power? (a) P = V ÷ I (b) P = V + I (c) P = I ÷ V (d) P = V × I
34. 34.🧮 Two resistors in parallel give a total that is … (a) less than either one (b) always zero (c) their sum (d) more than either one
35. 35.🔍 Which is the odd one out? (a) leave the TV on standby (b) use old filament bulbs (c) run fans in empty rooms (d) use LED lamps
36. 36.🔺 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
37. 37.🧮 Resistors of 220 Ω and 33 Ω are joined in series. What is the total resistance (in ohms)?
38. 38.🔍 Which is the odd one out? (a) set the AC to 24 °C (b) unplug idle chargers (c) leave the TV on standby (d) close the fridge quickly
39. 39.💡 Why does an LED need a resistor in series? (a) to store charge (b) to make it brighter (c) to change its colour (d) to limit the current
40. 40.What does an LDR do? (a) senses how bright it is (b) smooths a wobbly supply (c) senses how hot it is (d) has coloured bands

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