-->

Electrostatic Potential And Capacitance

Question
CBSEENPH12039800

A resistance 'R' draws power 'P' when connected to an AC source. If an inductance is now placed in series with the resistance such that the impedance of the circuit becomes 'Z' the power drawn will be

  • straight P open parentheses straight R over straight Z close parentheses squared
  • straight P square root of straight R over straight Z end root
  • straight P open parentheses straight R over straight Z close parentheses
  • P

Solution

A.

straight P open parentheses straight R over straight Z close parentheses squared

when a resistor is connected to an AC source. The power drawn will be 
P=Vrms.Irms
straight V subscript rms space. straight V subscript rms over straight R
rightwards double arrow space straight V subscript rms superscript 2 space equals space PR
When space an space inductor space is space connected space in space series space with space the space resistor comma space then space the space power
drawn space will space be
straight P apostrophe space equals straight V subscript rms. straight I subscript rms cosϕ
where space straight ϕ space equals space phase space difference
therefore space straight P apostrophe space equals space fraction numerator straight V subscript rms superscript 2 over denominator straight R end fraction. space straight R squared over straight Z squared space equals space straight P. straight R. straight R over straight Z squared
rightwards double arrow space straight P apostrophe space equals space fraction numerator straight P. straight R squared over denominator straight Z squared end fraction space equals space straight P open parentheses straight R over straight Z close parentheses squared

Some More Questions From Electrostatic Potential and Capacitance Chapter