Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 376 · 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: voltage is measured in amperes (A). (a) True (b) False
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.🧮 Two resistors in parallel give a total that is … (a) always zero (b) less than either one (c) their sum (d) more than either one
4. 4.💡 On an LED, is the round-side leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
5. 5.⚡ Power tells us … (a) the size of a cell (b) the colour of light (c) the length of a wire (d) energy used each second
6. 6.📏 How many milliamperes (mA) is 0.33 A?
7. 7.📏 How many kilowatts (kW) is 2450 W? =
8. 8.📏 How many ohms (Ω) is 8.8 kΩ?
9. 9.🔺 A current of 10 mA flows through a 470 Ω resistor. What is the voltage across it (in volts)? =
10. 10.True or false: a fuse blows if current is high. (a) False (b) True
11. 11.📏 How many amperes (A) is 3000 mA? =
12. 12.🔺 A current of 20 mA flows through a 150 Ω resistor. What is the voltage across it (in volts)? =
13. 13.🧮 Resistors of 100 Ω, 10 Ω and 68 Ω are joined in series. What is the total resistance (in ohms)?
14. 14.🧮 Adding another resistor in series makes the total resistance … (a) smaller (b) stay the same (c) zero (d) bigger
15. 15.🔺 A current of 2.5 A flows through an 8 Ω resistor. What is the voltage across it (in volts)? =
16. 16.True or false: on an LED, the longer leg is the cathode (−). (a) False (b) True
17. 17.🔺 In the V-I-R triangle, how do we find I? (a) I = V + R (b) I = R ÷ V (c) I = V × R (d) I = V ÷ R
18. 18.🌈 A gold fourth band on a resistor means the value may be off by … (a) 0 % (b) 50 % (c) 25 % (d) 5 %
19. 19.📏 Voltmeter or ammeter: which one measures voltage? (a) ammeter (b) voltmeter
20. 20.🔍 Which is the odd one out? (a) iron one shirt at a time (b) use old filament bulbs (c) leave the TV on standby (d) close the fridge quickly
21. 21.🧮 A 1.3 V battery is joined to 3 Ω and 10 Ω resistors in series. What current flows (in amperes)? =
22. 22.🧮 Five equal 250 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
23. 23.🧮 A 220 Ω resistor is joined in series with two equal 50 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
24. 24.💡 Does it save or waste electricity to set the AC to 24 °C? (a) wastes electricity (b) saves electricity
25. 25.💡 Does it save or waste electricity to leave the TV on standby? (a) saves electricity (b) wastes electricity
26. 26.🌈 A resistor has the colour bands brown, yellow, black. What is its value (in ohms)?
27. 27.🌈 A resistor has the colour bands white, blue, black. What is its value (in ohms)?
28. 28.🧩 Which component lets current go one way? (a) diode (b) fuse (c) LDR (d) motor
29. 29.🧾 A 100 W filament bulb is swapped for a 15 W LED lamp that gives about the same light. Both would run for 10 hours. How many watt-hours (Wh) are saved?
30. 30.💡 What happens if an LED is put in backwards? (a) it lights brighter (b) it changes colour (c) it does not light (d) it makes a sound
31. 31.⚡ A home appliance on the 230 V mains takes 0.5 A. What is its power (in watts)?
32. 32.Which of these saves electricity? (a) run fans in empty rooms (b) leave fridge door open (c) use old filament bulbs (d) use LED lamps
33. 33.🔺 A 4 V supply is joined across a 400 Ω resistor. What current flows (in milliamperes, mA)?
34. 34.What does a potentiometer do? (a) glows using little power (b) beeps for an alarm (c) has coloured bands (d) is a resistance knob
35. 35.⚡ A device works on 3 V and takes 1.5 A. What is its power (in watts)? =
36. 36.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 26000 Ω resistor? (a) blue-red-orange (b) red-blue-orange (c) red-blue-red (d) red-blue-yellow
37. 37.⚡ A device works on 1.5 V and takes 0.1 A. What is its power (in watts)? =
38. 38.True or false: a capacitor stores a little charge. (a) False (b) True
39. 39.🔍 Which is the odd one out? (a) set the AC to 24 °C (b) switch off empty rooms (c) run fans in empty rooms (d) use daylight to read
40. 40.🌈 A resistor has the colour bands yellow, brown, yellow. What is its value in kilo-ohms (kΩ)? =

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