Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 593 · 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: a capacitor has coloured bands. (a) True (b) False
2. 2.True or false: on an LED, the leg by the flat edge is the cathode (−). (a) False (b) True
3. 3.🔺 A current of 40 mA flows through a 200 Ω resistor. What is the voltage across it (in volts)? =
4. 4.💡 A red LED (it uses 2 V) is joined with a 100 Ω resistor to a 3.5 V supply. What current flows (in mA)?
5. 5.💡 On an LED, is the shorter leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
6. 6.🔺 In the V-I-R triangle, how do we find V? (a) V = I × R (b) V = R ÷ I (c) V = I + R (d) V = I ÷ R
7. 7.🔺 A current of 10 mA flows when 2.2 V is joined across a resistor. What is its resistance (in ohms)?
8. 8.🌈 In the resistor colour code, which number does brown stand for?
9. 9.True or false: voltage is measured in volts (V). (a) True (b) False
10. 10.🌈 A resistor has the colour bands violet, red, red. What is its value in kilo-ohms (kΩ)? =
11. 11.💡 Does it save or waste electricity to leave the TV on standby? (a) saves electricity (b) wastes electricity
12. 12.True or false: resistance is measured in ohms (Ω). (a) False (b) True
13. 13.💡 On an LED, is the round-side leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
14. 14.⚡ Which formula gives electric power? (a) P = I ÷ V (b) P = V + I (c) P = V × I (d) P = V ÷ I
15. 15.True or false: an LDR senses how bright it is. (a) False (b) True
16. 16.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 12 Ω resistor? (a) brown-red-brown (b) red-red-black (c) brown-red-black (d) red-brown-black
17. 17.What does a potentiometer do? (a) has coloured bands (b) turns a fan or wheels (c) boosts a small signal (d) is a resistance knob
18. 18.📏 Which unit measures energy used each second? (a) ampere (A) (b) ohm (Ω) (c) volt (V) (d) watt (W)
19. 19.True or false: a transistor senses how bright it is. (a) False (b) True
20. 20.True or false: to close the fridge quickly wastes electricity. (a) False (b) True
21. 21.🔺 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
22. 22.True or false: current is measured in amperes (A). (a) True (b) False
23. 23.⚡ 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
24. 24.🔺 A current of 0.2 A flows through a 5 Ω resistor. What is the voltage across it (in volts)? =
25. 25.True or false: the push of a cell is measured in ohms (Ω). (a) True (b) False
26. 26.🧮 Adding another resistor in series makes the total resistance … (a) zero (b) smaller (c) bigger (d) stay the same
27. 27.Which of these is measured in watts (W)? (a) power (b) voltage (c) how much a part resists (d) the flow of charge
28. 28.🧮 Two resistors in parallel give a total that is … (a) less than either one (b) always zero (c) more than either one (d) their sum
29. 29.🌈 A resistor has the colour bands red, black, black. What is its value (in ohms)?
30. 30.🌈 A resistor has the colour bands violet, brown, brown. What is its value (in ohms)?
31. 31.🔺 In the V-I-R triangle, how do we find R? (a) R = I ÷ V (b) R = V × I (c) R = V ÷ I (d) R = V + I
32. 32.Which of these wastes electricity? (a) iron one shirt at a time (b) use LED lamps (c) close the fridge quickly (d) set the AC to 24 °C
33. 33.🔺 A current of 25 mA flows when 6.25 V is joined across a resistor. What is its resistance (in ohms)?
34. 34.💡 An LED is joined to a 5 V battery through a 470 Ω resistor; the leg next to the flat edge of its rim goes to the + side. What happens? (a) lights up (b) does not light (c) may burn out
35. 35.💡 A red LED (it uses 2 V) is joined with a 100 Ω resistor to a 4 V supply. What current flows (in mA)?
36. 36.🧾 Which lamp gives the same light for the least power? (a) a filament bulb (b) a candle (c) an LED lamp (d) an oil lamp
37. 37.🔺 A current of 0.25 A flows when 2.5 V is joined across a resistor. What is its resistance (in ohms)?
38. 38.🌈 A resistor has the colour bands yellow, black, red. What is its value in kilo-ohms (kΩ)? =
39. 39.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) gets bigger (b) gets smaller (c) stays the same (d) becomes zero
40. 40.⚡ A device works on 1.5 V and takes 0.1 A. What is its power (in watts)? =

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