# Ncert 12th Physics Chapter-7

## Wattless Current

Chapter-7|Alternating Current |NCERT 12th Physics: Wattless Current: The current which consumes no power for its maintenance in the circuit is called wattless current of idle current.  Or The current in AC circuit is said to be wattless if the average power consumed in the circuit is zero. The average power of a given circuit is […]

## Transformer

Chapter-7|Alternating Current |NCERT 12th Physics: Transformer: It is a device which is used to increase or decrease the alternating voltage. The Transformer are two types (I) Step-Up transformer – Increase voltage (II) Step-down transformer – Decrease voltage Construction: It consists of large number of laminated soft iron cores. There are two types of winding one

## Energy Stored in an Inductor

Chapter-7|Alternating Current |NCERT 12th Physics: Energy Stored in an Inductor: When in inductor(L), current(I) is applied, the magnetic flux will be developed.

## L-C Oscillations

Chapter-7|Alternating Current |NCERT 12th Physics: L-C Oscillations: When a capacitor is supplied with AC current, it gets charged When this charged capacitor is connected with an inductor, current flows through inductor, giving rise to magnetic flux. Hence, induced EMF is produced in this circuit. Due to this, the charge of the capacitor decreases and an

## Resonance in L-C-R Circuit || Power in AC Circuit

Chapter-7|Alternating Current |NCERT 12th Physics: Resonance in L-C-R Circuit: In LCR circuit, when phase(Ø) between current and voltage is zero, the circuit is said to be resonant circuit. Power in AC Circuit: We know that,  V= V₀Sinωt  applied to a series LCR circuit drives a current in the circuit.

## AC Circuit || AC Voltage Applied to a Series LCR Circuit

Chapter-7|Alternating Current |NCERT 12th Physics: AC Voltage Applied to a Series LCR Circuit: Let an inductor(L), a capacitor (C) and resistance (R) are connected in series to an AC source.

## AC Circuit || AC Voltage Applied to a Capacitor

Chapter-7|Alternating Current |NCERT 12th Physics: AC Voltage Applied to a Capacitor: Let a capacitor with capacitance C be connected to an AC source with EMF Due to this EMF, charge will be produced and it will charge the plate of capacitor with positive and negative charge. If potential difference across the plates of capacitor is

## AC Circuit|| AC Voltage Applied to an Inductor

Chapter-7|Alternating Current |NCERT 12th Physics: AC Voltage Applied to an Inductor: Let an inductor with self inductance(L) is connected to an AC source with instantaneous EMF (V) which is given by               V= V₀Sinωt Applying Kirchhoff’s law, Net potential across the circuit will be zero Phase difference: Phase angle

## AC Circuit || AC Voltage Applied to a Resistor

Chapter-7|Alternating Current |NCERT 12th Physics: AC Voltage Applied to a Resistor: Let a resistor of resistance R is connected to an AC source of EMF with instantaneous value V, which is given by            V= V₀Sinωt   Or (E= E₀Sinωt) Comparing I₀= V₀/R with Ohm’s law, we find that registers work equally well for

## Root Mean Square(RMS) Value of AC

Chapter-7|Alternating Current |NCERT 12th Physics: Root Mean Square(RMS) Value of AC: It is defined as the value of AC over a complete cycle which would generate same amount of heat in a given register that is generated by steady(DC) current in the same register and in the same time during a complete cycle. Derivation: We

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