# Which of the following bulb will glow more brightly than the others?

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Which of the following bulb will glow more brightly than the others?
1. A bulb with 220 V supply and resistance of 100 ohm
2. A bulb with 220 V supply and resistance of 50 ohm
3. A bulb with 110 V supply and resistance of 100 ohm
4. A bulb with 110 V supply and resistance of 50 ohm

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Correct Answer - Option 2 : A bulb with 220 V supply and resistance of 50 ohm

CONCEPT:

• Resistance: The opposition of the flow of current in an electrical circuit is called its resistance.
• Ohm's Law: A law that states that electric current is proportional to voltage and inversely proportional to resistance.
• Mathematically it is written as,

⇒ V = IR or I = V/R

where R is the resistance, I is current, and V is the voltage across the conductor.

Power in resistance:

$⇒ P=VI = {V^2\over R}=I^2R$

where I is the current and  V is the voltage.

• If the power of the bulb increases, the bulb will become brighter than before.

EXPLANATION:

• Option 1: V = 220 volt and R = 100 Ω

$⇒ P_1= {V^2\over R}= {220^2\over 100}=484 watt$

• Option 2: V = 220 volt and R = 50 Ω

$⇒ P_2= {V^2\over R}= {220^2\over 50}=968 watt$

• Option 3: V = 110 volt and R = 100 Ω

$⇒ P_3= {V^2\over R}= {110^2\over 100}=121 watt$

• Option 4: V = 110 volt and R = 50 Ω

$⇒ P_4= {V^2\over R}= {110^2\over 50}=242 watt$

• Clearly, the power of the bulb in option 2 is greater than the other.
• We know that If the power of the bulb increases, the bulb will become brighter than before.
• So the bulb in option 2 will glow more brightly than the others. Therefore, the correct answer is option 2.