Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 406 · 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.🧩 Which component boosts a small signal? (a) capacitor (b) LED (c) transistor (d) buzzer
2. 2.🔺 In the V-I-R triangle, how do we find V? (a) V = I ÷ R (b) V = I × R (c) V = R ÷ I (d) V = I + R
3. 3.🧮 A 10 V battery is joined to 10 Ω and 10 Ω resistors in series. What current flows (in amperes)? =
4. 4.⚡ A device works on 6 V and takes 3 A. What is its power (in watts)? =
5. 5.🌈 Which band is read first on a resistor? (a) the widest gap (b) the gold band (c) the one nearest an end (d) any band
6. 6.⚡ Which formula gives electric power? (a) P = I ÷ V (b) P = V ÷ I (c) P = V + I (d) P = V × I
7. 7.🧩 Which component senses how hot it is? (a) transistor (b) thermistor (c) LDR (d) diode
8. 8.💡 On an LED, is the shorter leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
9. 9.💡 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
10. 10.🔺 A current of 0.2 A flows when 0.6 V is joined across a resistor. What is its resistance (in ohms)?
11. 11.What does a potentiometer do? (a) senses how bright it is (b) turns a fan or wheels (c) is a resistance knob (d) stores a little charge
12. 12.🔺 A current of 10 mA flows when 1.5 V is joined across a resistor. What is its resistance (in ohms)?
13. 13.📏 How many ohms make 1 kilo-ohm (kΩ)? (a) 100 (b) 1024 (c) 1000 (d) 10
14. 14.💡 A red LED (it uses 2 V) is joined with a 100 Ω resistor to a 4 V supply. What current flows (in mA)?
15. 15.🧮 Three equal 15 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
16. 16.🔺 A current of 50 mA flows when 7.5 V is joined across a resistor. What is its resistance (in ohms)?
17. 17.💡 What does LED stand for? (a) light-emitting diode (b) large electric dial (c) low energy device (d) light energy dial
18. 18.🧩 Which component senses how bright it is? (a) transistor (b) LDR (c) resistor (d) motor
19. 19.🧩 Which component lets current go one way? (a) potentiometer (b) motor (c) diode (d) LDR
20. 20.⚡ A home appliance on the 230 V mains takes 4 A. What is its power (in watts)?
21. 21.🔺 A current of 1 A flows through a 5 Ω resistor. What is the voltage across it (in volts)? =
22. 22.📏 Voltmeter or ammeter: which one measures current? (a) voltmeter (b) ammeter
23. 23.🧾 One “unit” on an electricity bill is … (a) 1 ampere (b) 1 volt (c) 1 watt (d) 1 kilowatt-hour (kWh)
24. 24.⚡ A home appliance on the 230 V mains takes 1 A. What is its power (in watts)?
25. 25.🌈 A gold fourth band on a resistor means the value may be off by … (a) 25 % (b) 5 % (c) 0 % (d) 50 %
26. 26.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 9400 Ω resistor? (a) yellow-white-red (b) white-yellow-orange (c) white-yellow-brown (d) white-yellow-red
27. 27.🌈 A resistor has the colour bands grey, blue, orange. What is its value (in ohms)?
28. 28.🧮 A 3.6 V battery is joined to 12 Ω and 6 Ω resistors in series. What current flows (in amperes)? =
29. 29.🧮 Two resistors in parallel give a total that is … (a) always zero (b) their sum (c) more than either one (d) less than either one
30. 30.⚡ A home appliance on the 230 V mains takes 10 A. What is its power (in watts)?
31. 31.🧮 A 10 Ω resistor is joined in series with two equal 10 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
32. 32.⚡ A device works on 12 V and takes 0.2 A. What is its power (in watts)? =
33. 33.💡 On an LED, is the round-side leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
34. 34.🧮 Two equal 220 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
35. 35.⚡ A home appliance on the 230 V mains takes 5 A. What is its power (in watts)?
36. 36.📏 How many watts (W) is 4.2 kW?
37. 37.True or false: a resistor limits the current. (a) False (b) True
38. 38.True or false: on an LED, the longer leg is the anode (+). (a) True (b) False
39. 39.🔺 A 3.3 V supply is joined across a 330 Ω resistor. What current flows (in milliamperes, mA)?
40. 40.🌈 In the resistor colour code, which number does brown stand for?

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