Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 52 · 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.🔺 A 0.5 V supply is joined across a 2 Ω resistor. What current flows (in amperes)? =
2. 2.🔺 In the V-I-R triangle, how do we find R? (a) R = V ÷ I (b) R = I ÷ V (c) R = V + I (d) R = V × I
3. 3.🌈 A resistor has the colour bands orange, violet, brown. What is its value (in ohms)?
4. 4.🔺 A 3 V supply is joined across a 150 Ω resistor. What current flows (in milliamperes, mA)?
5. 5.🔺 A 13.2 V supply is joined across a 330 Ω resistor. What current flows (in milliamperes, mA)?
6. 6.🌈 In the resistor colour code, which number does brown stand for?
7. 7.💡 What happens if an LED is put in backwards? (a) it does not light (b) it changes colour (c) it lights brighter (d) it makes a sound
8. 8.📏 Which unit measures the flow of charge? (a) ohm (Ω) (b) volt (V) (c) ampere (A) (d) watt (W)
9. 9.🧾 One “unit” on an electricity bill is … (a) 1 ampere (b) 1 kilowatt-hour (kWh) (c) 1 volt (d) 1 watt
10. 10.True or false: a buzzer makes a beeping sound. (a) False (b) True
11. 11.What does a thermistor do? (a) glows using little power (b) boosts a small signal (c) lets current go one way (d) senses how hot it is
12. 12.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 68000 Ω resistor? (a) blue-grey-yellow (b) grey-blue-orange (c) blue-grey-orange (d) blue-grey-red
13. 13.🧮 Two resistors in parallel give a total that is … (a) their sum (b) less than either one (c) more than either one (d) always zero
14. 14.💡 An LED is joined to a 5 V battery with no resistor; its long leg goes to the + side and its short leg to the − side. What happens? (a) may burn out (b) lights up (c) does not light
15. 15.⚡ Power tells us … (a) the colour of light (b) the length of a wire (c) the size of a cell (d) energy used each second
16. 16.🔍 Which is the odd one out? (a) iron one shirt at a time (b) use old filament bulbs (c) leave fridge door open (d) use LED lamps
17. 17.🌈 In the resistor colour code, which number does grey stand for?
18. 18.True or false: on an LED, the longer leg is the cathode (−). (a) True (b) False
19. 19.Which of these is measured in amperes (A)? (a) voltage (b) resistance (c) the flow of charge (d) power
20. 20.🧾 A 60 W filament bulb is swapped for a 9 W LED lamp that gives about the same light. Both would run for 7 hours. How many watt-hours (Wh) are saved?
21. 21.⚡ A device works on 5 V and takes 0.2 A. What is its power (in watts)? =
22. 22.🧾 A family uses 100 units of electricity in a month and each unit costs ₹6. What is the bill (in ₹)?
23. 23.🔺 A current of 10 mA flows through a 250 Ω resistor. What is the voltage across it (in volts)? =
24. 24.⚡ A device works on 1.5 V and takes 0.25 A. What is its power (in watts)? =
25. 25.🧮 A 330 Ω resistor is joined in series with two equal 1000 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
26. 26.🔺 A current of 10 mA flows through a 120 Ω resistor. What is the voltage across it (in volts)? =
27. 27.🔺 A current of 40 mA flows through a 220 Ω resistor. What is the voltage across it (in volts)? =
28. 28.🧮 A 2 V battery is joined to 8 Ω and 12 Ω resistors in series. What current flows (in amperes)? =
29. 29.What does an LDR do? (a) limits the current (b) makes a beeping sound (c) senses how bright it is (d) is a resistance knob
30. 30.🔺 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
31. 31.🔺 A 2.2 V supply is joined across a 220 Ω resistor. What current flows (in milliamperes, mA)?
32. 32.⚡ A home appliance on the 230 V mains takes 10 A. What is its power (in watts)?
33. 33.What does a transistor do? (a) boosts a small signal (b) stores a little charge (c) senses how hot it is (d) makes things spin
34. 34.🔺 A current of 0.25 A flows through a 15 Ω resistor. What is the voltage across it (in volts)? =
35. 35.🔺 A current of 3 A flows when 18 V is joined across a resistor. What is its resistance (in ohms)?
36. 36.💡 Why does an LED need a resistor in series? (a) to store charge (b) to limit the current (c) to make it brighter (d) to change its colour
37. 37.📏 Voltmeter or ammeter: which one measures voltage? (a) voltmeter (b) ammeter
38. 38.🔺 A current of 0.25 A flows when 2 V is joined across a resistor. What is its resistance (in ohms)?
39. 39.🔺 A 0.75 V supply is joined across a 3 Ω resistor. What current flows (in amperes)? =
40. 40.🌈 A gold fourth band on a resistor means the value may be off by … (a) 5 % (b) 0 % (c) 50 % (d) 25 %

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