Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 950 · 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.💡 On an LED, is the round-side leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
2. 2.🌈 A gold fourth band on a resistor means the value may be off by … (a) 5 % (b) 25 % (c) 0 % (d) 50 %
3. 3.🔺 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
4. 4.🔺 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
5. 5.🔺 A 4 V supply is joined across a 400 Ω resistor. What current flows (in milliamperes, mA)?
6. 6.True or false: a diode makes things spin. (a) True (b) False
7. 7.🧾 A family uses 180 units of electricity in a month and each unit costs ₹6. What is the bill (in ₹)?
8. 8.🔺 A current of 0.5 A flows through a 2 Ω resistor. What is the voltage across it (in volts)? =
9. 9.Which of these is measured in ohms (Ω)? (a) how much a part resists (b) energy used each second (c) current (d) voltage
10. 10.⚡ Power tells us … (a) the size of a cell (b) energy used each second (c) the colour of light (d) the length of a wire
11. 11.🔺 A current of 10 mA flows through a 330 Ω resistor. What is the voltage across it (in volts)? =
12. 12.🧮 An 18 V battery is joined to 6 Ω and 12 Ω resistors in series. What current flows (in amperes)? =
13. 13.🔺 A current of 3 A flows when 24 V is joined across a resistor. What is its resistance (in ohms)?
14. 14.📏 How many ohms (Ω) is 9.2 kΩ?
15. 15.📏 Voltmeter or ammeter: which one measures voltage? (a) ammeter (b) voltmeter
16. 16.🌈 A resistor has the colour bands brown, black, orange. What is its value in kilo-ohms (kΩ)? =
17. 17.📏 Which unit measures voltage? (a) watt (W) (b) ampere (A) (c) ohm (Ω) (d) volt (V)
18. 18.🔺 A current of 1.5 A flows through a 6 Ω resistor. What is the voltage across it (in volts)? =
19. 19.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 200 Ω resistor? (a) red-black-red (b) red-black-black (c) orange-red-brown (d) red-black-brown
20. 20.🔺 A 20 V supply is joined across a 10 Ω resistor. What current flows (in amperes)? =
21. 21.⚡ A 7.5 W device works on 5 V. What current does it take (in amperes)? =
22. 22.🔍 Which is the odd one out? (a) leave the TV on standby (b) leave fridge door open (c) use old filament bulbs (d) set the AC to 24 °C
23. 23.💡 An LED is joined to a 3 V battery through a 220 Ω resistor; the leg next to the flat edge of its rim goes to the + side. What happens? (a) may burn out (b) lights up (c) does not light
24. 24.True or false: on an LED, the longer leg is the cathode (−). (a) True (b) False
25. 25.⚡ Which formula gives electric power? (a) P = V + I (b) P = I ÷ V (c) P = V ÷ I (d) P = V × I
26. 26.🔺 A current of 10 mA flows through a 400 Ω resistor. What is the voltage across it (in volts)? =
27. 27.🌈 A resistor has the colour bands red, black, red. What is its value (in ohms)?
28. 28.🧾 A 40 W filament bulb is swapped for a 6 W LED lamp that gives about the same light. Both would run for 10 hours. How many watt-hours (Wh) are saved?
29. 29.🧩 Which component senses how hot it is? (a) fuse (b) capacitor (c) LED (d) thermistor
30. 30.🧾 A family uses 120 units of electricity in a month and each unit costs ₹7. What is the bill (in ₹)?
31. 31.🧩 Which component makes things spin? (a) transistor (b) buzzer (c) thermistor (d) motor
32. 32.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) gets smaller (b) gets bigger (c) becomes zero (d) stays the same
33. 33.⚡ A device works on 3 V and takes 0.25 A. What is its power (in watts)? =
34. 34.🔺 A current of 20 mA flows when 6 V is joined across a resistor. What is its resistance (in ohms)?
35. 35.🔺 A 2 V supply is joined across a 20 Ω resistor. What current flows (in amperes)? =
36. 36.🧮 Resistors of 330 Ω, 470 Ω and 10 Ω are joined in series. What is the total resistance (in ohms)?
37. 37.🌈 A resistor has the colour bands violet, orange, red. What is its value (in ohms)?
38. 38.🧾 One “unit” on an electricity bill is … (a) 1 watt (b) 1 kilowatt-hour (kWh) (c) 1 ampere (d) 1 volt
39. 39.📏 How many watts (W) is 4.9 kW?
40. 40.🌈 Which band is read first on a resistor? (a) any band (b) the widest gap (c) the gold band (d) the one nearest an end

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