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Physics - Current Electricity Question with Solution | TestHub

PhysicsCurrent ElectricityElectrical PowerMedium2 minQB

PhysicsMediumsingle choice

Water boils in an electric kettle in 20 minutes after being switched on. Using the same main supply, the length of the heating element should be _____ to _____ times of its initial length if the water is to be boiled in 15 minutes.

Options:

Answer:

Solution:

$P = \frac{v ^{2}}{R}, R = \frac{ρ ℓ}{A} P \propto \frac{1}{ℓ} \frac{P _{1}}{P _{2}} = \frac{t _{2}}{t _{1}} = \frac{15}{20} = \frac{ℓ _{2}}{ℓ _{1}} ℓ_{2} = \frac{3}{4} ℓ_{1}$

Stream:JEESubject:PhysicsTopic:Current ElectricitySubtopic:Electrical Power

⏱ 2mℹ️ Source: QB

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