Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 41 · 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.📏 How many milliamperes (mA) is 1.36 A?
2. 2.Which of these saves electricity? (a) unplug idle chargers (b) iron one shirt at a time (c) use old filament bulbs (d) leave fridge door open
3. 3.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) gets bigger (b) gets smaller (c) becomes zero (d) stays the same
4. 4.🔺 A current of 20 mA flows through a 470 Ω resistor. What is the voltage across it (in volts)? =
5. 5.🧾 One “unit” on an electricity bill is … (a) 1 volt (b) 1 kilowatt-hour (kWh) (c) 1 watt (d) 1 ampere
6. 6.🔺 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
7. 7.⚡ A home appliance on the 230 V mains takes 1 A. What is its power (in watts)?
8. 8.📏 How many watts (W) is 0.3 kW?
9. 9.⚡ A home appliance on the 230 V mains takes 4 A. What is its power (in watts)?
10. 10.True or false: a resistor senses how hot it is. (a) False (b) True
11. 11.🔺 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
12. 12.🧮 Two equal 1000 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
13. 13.💡 A red LED (it uses 2 V) is joined with a 150 Ω resistor to a 3.5 V supply. What current flows (in mA)?
14. 14.Which of these is measured in volts (V)? (a) the push of a cell (b) resistance (c) current (d) energy used each second
15. 15.🧮 Four equal 80 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
16. 16.🌈 A resistor has the colour bands yellow, black, yellow. What is its value in kilo-ohms (kΩ)? =
17. 17.📏 Which unit measures the flow of charge? (a) ohm (Ω) (b) volt (V) (c) ampere (A) (d) watt (W)
18. 18.🌈 A gold fourth band on a resistor means the value may be off by … (a) 50 % (b) 0 % (c) 25 % (d) 5 %
19. 19.💡 An LED is joined to a 6 V battery through a 1000 Ω resistor; the leg next to the flat edge of its rim goes to the − side. What happens? (a) may burn out (b) does not light (c) lights up
20. 20.💡 Does it save or waste electricity to run fans in empty rooms? (a) wastes electricity (b) saves electricity
21. 21.🧩 Which component makes a beeping sound? (a) fuse (b) buzzer (c) LDR (d) thermistor
22. 22.🔺 A current of 10 mA flows through a 300 Ω resistor. What is the voltage across it (in volts)? =
23. 23.🧾 A 1000 W appliance runs for 8 hours. How many units (kWh) of electricity does it use? =
24. 24.🔺 A current of 20 mA flows when 2.4 V is joined across a resistor. What is its resistance (in ohms)?
25. 25.📏 In the water-pipe picture of a circuit, current is like … (a) a narrow pipe (b) the water pressure (c) the flow of water (d) the pipe colour
26. 26.True or false: voltage is measured in volts (V). (a) True (b) False
27. 27.True or false: a resistor has coloured bands. (a) False (b) True
28. 28.🌈 A resistor has the colour bands green, red, red. What is its value in kilo-ohms (kΩ)? =
29. 29.🌈 In the resistor colour code, which number does white stand for?
30. 30.🔺 A current of 40 mA flows through a 200 Ω resistor. What is the voltage across it (in volts)? =
31. 31.📏 Voltmeter or ammeter: which one is joined in series? (a) voltmeter (b) ammeter
32. 32.🧩 Which component is a resistance knob? (a) LDR (b) potentiometer (c) buzzer (d) transistor
33. 33.True or false: a motor beeps for an alarm. (a) True (b) False
34. 34.🔺 In the V-I-R triangle, how do we find R? (a) R = I ÷ V (b) R = V ÷ I (c) R = V × I (d) R = V + I
35. 35.⚡ Power tells us … (a) energy used each second (b) the length of a wire (c) the colour of light (d) the size of a cell
36. 36.🧮 A 470 Ω resistor is joined in series with two equal 330 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
37. 37.True or false: a capacitor blows if current is high. (a) True (b) False
38. 38.💡 What happens if an LED is put in backwards? (a) it changes colour (b) it lights brighter (c) it does not light (d) it makes a sound
39. 39.⚡ A device works on 3 V and takes 2 A. What is its power (in watts)? =
40. 40.🧩 Which part changes electrical energy into movement? (a) a resistor (b) a motor (c) an LED (d) a fuse

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