Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 627 · 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.⚡ Power tells us … (a) energy used each second (b) the size of a cell (c) the colour of light (d) the length of a wire
2. 2.What does a buzzer do? (a) boosts a small signal (b) smooths a wobbly supply (c) has coloured bands (d) makes a beeping sound
3. 3.⚡ Which formula gives electric power? (a) P = V + I (b) P = V ÷ I (c) P = I ÷ V (d) P = V × I
4. 4.🔺 In the V-I-R triangle, how do we find I? (a) I = R ÷ V (b) I = V + R (c) I = V ÷ R (d) I = V × R
5. 5.🧮 Resistors of 150 Ω, 100 Ω, 150 Ω and 68 Ω are joined in series. What is the total resistance (in ohms)?
6. 6.🧮 Two equal 100 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
7. 7.🔍 Which is the odd one out? (a) leave the TV on standby (b) leave fridge door open (c) use daylight to read (d) use old filament bulbs
8. 8.🧾 A 500 W appliance runs for 10 hours. How many units (kWh) of electricity does it use? =
9. 9.True or false: on an LED, the longer leg is the anode (+). (a) False (b) True
10. 10.🔺 A current of 50 mA flows when 16.5 V is joined across a resistor. What is its resistance (in ohms)?
11. 11.🔺 A current of 0.5 A flows through a 10 Ω resistor. What is the voltage across it (in volts)? =
12. 12.🔺 A current of 25 mA flows through a 400 Ω resistor. What is the voltage across it (in volts)? =
13. 13.🧾 A 100 W appliance runs for 6 hours. How many units (kWh) of electricity does it use? =
14. 14.True or false: the ammeter is joined in series. (a) True (b) False
15. 15.🔺 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
16. 16.🌈 In the resistor colour code, which number does violet stand for?
17. 17.🧩 A capacitor in a circuit can … (a) spin a wheel (b) make light (c) measure heat (d) store charge briefly
18. 18.🔺 A 10 V supply is joined across a 10 Ω resistor. What current flows (in amperes)? =
19. 19.🔺 A current of 1.5 A flows through a 15 Ω resistor. What is the voltage across it (in volts)? =
20. 20.True or false: an LDR beeps for an alarm. (a) False (b) True
21. 21.⚡ A home appliance on the 230 V mains takes 1 A. What is its power (in watts)?
22. 22.Which of these saves electricity? (a) set the AC to 24 °C (b) leave the TV on standby (c) run fans in empty rooms (d) iron one shirt at a time
23. 23.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 370 Ω resistor? (a) orange-violet-black (b) violet-orange-brown (c) orange-violet-red (d) orange-violet-brown
24. 24.📏 How many kilo-ohms (kΩ) is 2000 Ω? =
25. 25.💡 On an LED, is the shorter leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
26. 26.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 700 Ω resistor? (a) violet-black-black (b) violet-black-brown (c) grey-violet-brown (d) violet-black-red
27. 27.What does a potentiometer do? (a) senses how hot it is (b) is a resistance knob (c) senses how bright it is (d) stores a little charge
28. 28.🧾 One “unit” on an electricity bill is … (a) 1 watt (b) 1 ampere (c) 1 kilowatt-hour (kWh) (d) 1 volt
29. 29.True or false: on an LED, the shorter leg is the anode (+). (a) True (b) False
30. 30.🔺 A current of 1 A flows through an 8 Ω resistor. What is the voltage across it (in volts)? =
31. 31.🧮 Two resistors in parallel give a total that is … (a) more than either one (b) their sum (c) always zero (d) less than either one
32. 32.💡 On an LED, is the leg by the flat edge the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
33. 33.🧩 Which component senses how hot it is? (a) diode (b) LED (c) thermistor (d) motor
34. 34.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) stays the same (b) gets smaller (c) becomes zero (d) gets bigger
35. 35.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 42 Ω resistor? (a) yellow-red-black (b) yellow-red-brown (c) green-red-black (d) red-yellow-black
36. 36.True or false: the push of a cell is measured in ohms (Ω). (a) False (b) True
37. 37.What does a motor do? (a) blows if current is high (b) turns a fan or wheels (c) stores a little charge (d) beeps for an alarm
38. 38.Which of these is measured in ohms (Ω)? (a) current (b) energy used each second (c) resistance (d) power
39. 39.🌈 A gold fourth band on a resistor means the value may be off by … (a) 5 % (b) 50 % (c) 0 % (d) 25 %
40. 40.🧮 Five equal 250 Ω resistors are joined in parallel. What is the total resistance (in ohms)?

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