Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 198 · 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 of these is measured in amperes (A)? (a) voltage (b) current (c) energy used each second (d) power
2. 2.Which of these saves electricity? (a) leave fridge door open (b) iron one shirt at a time (c) use daylight to read (d) run fans in empty rooms
3. 3.🔺 A current of 10 mA flows when 1 V is joined across a resistor. What is its resistance (in ohms)?
4. 4.🧾 A 200 W appliance runs for 8 hours. How many units (kWh) of electricity does it use? =
5. 5.💡 A blue LED uses 3 V and should get 20 mA. It runs from a 12 V supply. What resistor (in ohms) is needed in series?
6. 6.💡 Does it save or waste electricity to unplug idle chargers? (a) saves electricity (b) wastes electricity
7. 7.💡 On an LED, is the longer leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
8. 8.🔺 A current of 0.2 A flows through a 10 Ω resistor. What is the voltage across it (in volts)? =
9. 9.🌈 In the resistor colour code, which number does grey stand for?
10. 10.🔺 A 0.6 V supply is joined across a 3 Ω resistor. What current flows (in amperes)? =
11. 11.⚡ A home appliance on the 230 V mains takes 1 A. What is its power (in watts)?
12. 12.True or false: on an LED, the longer leg is the cathode (−). (a) True (b) False
13. 13.🌈 A resistor has the colour bands brown, brown, brown. What is its value (in ohms)?
14. 14.🔺 A current of 10 mA flows when 1.5 V is joined across a resistor. What is its resistance (in ohms)?
15. 15.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) gets bigger (b) becomes zero (c) stays the same (d) gets smaller
16. 16.🧾 One “unit” on an electricity bill is … (a) 1 watt (b) 1 volt (c) 1 kilowatt-hour (kWh) (d) 1 ampere
17. 17.🔺 In the V-I-R triangle, how do we find I? (a) I = V + R (b) I = V ÷ R (c) I = R ÷ V (d) I = V × R
18. 18.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 53 Ω resistor? (a) orange-green-black (b) blue-orange-black (c) green-orange-black (d) green-orange-brown
19. 19.🧩 Which part changes electrical energy into movement? (a) a resistor (b) an LED (c) a motor (d) a fuse
20. 20.🌈 A gold fourth band on a resistor means the value may be off by … (a) 25 % (b) 50 % (c) 0 % (d) 5 %
21. 21.💡 Does it save or waste electricity to close the fridge quickly? (a) saves electricity (b) wastes electricity
22. 22.💡 What happens if an LED is put in backwards? (a) it does not light (b) it changes colour (c) it makes a sound (d) it lights brighter
23. 23.⚡ An 18 W device works on 12 V. What current does it take (in amperes)? =
24. 24.What does a transistor do? (a) makes things spin (b) limits the current (c) is a resistance knob (d) boosts a small signal
25. 25.📏 How many milliamperes (mA) is 1.39 A?
26. 26.🔺 A 1.5 V supply is joined across a 6 Ω resistor. What current flows (in amperes)? =
27. 27.🌈 Which band is read first on a resistor? (a) the one nearest an end (b) any band (c) the widest gap (d) the gold band
28. 28.🧮 Two resistors in parallel give a total that is … (a) always zero (b) less than either one (c) more than either one (d) their sum
29. 29.🔺 A current of 0.1 A flows when 0.5 V is joined across a resistor. What is its resistance (in ohms)?
30. 30.🔺 A current of 0.5 A flows through a 3 Ω resistor. What is the voltage across it (in volts)? =
31. 31.🔍 Which is the odd one out? (a) set the AC to 24 °C (b) iron one shirt at a time (c) close the fridge quickly (d) switch off empty rooms
32. 32.Which of these is measured in watts (W)? (a) power (b) the push of a cell (c) how much a part resists (d) the flow of charge
33. 33.🌈 A resistor has the colour bands blue, black, red. What is its value (in ohms)?
34. 34.True or false: the ammeter is joined across a part. (a) True (b) False
35. 35.🧮 Resistors of 470 Ω, 20 Ω and 220 Ω are joined in series. What is the total resistance (in ohms)?
36. 36.🌈 In the resistor colour code, which number does yellow stand for?
37. 37.📏 In the water-pipe picture of a circuit, current is like … (a) the pipe colour (b) the flow of water (c) the water pressure (d) a narrow pipe
38. 38.🧩 Which component beeps for an alarm? (a) LDR (b) buzzer (c) LED (d) diode
39. 39.🧮 Resistors of 50 Ω and 220 Ω are joined in series. What is the total resistance (in ohms)?
40. 40.🔺 A current of 20 mA flows when 6 V is joined across a resistor. What is its resistance (in ohms)?

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