# Ncert 12th Physics Chapter-4

## Conversion of Galvanometer to Voltmeter

Chapter-4|Moving Charges and Magnetism| NCERT 12th Physics: Conversion of Galvanometer to Voltmeter: Voltmeter: A device used to measure potential difference in a appliance. Voltmeter is always connected in parallel with appliance.   Important Concept: The resistance of an ideal voltmeter should be infinity. Example: A voltmeter whose coil has resistance 10 ohm, gives full scale […]

## Conversion of Galvanometer Into an Ammeter

Chapter-4|Moving Charges and Magnetism| NCERT 12th Physics: Conversion of Galvanometer Into an Ammeter: Ammeter: A device used to measure electric current. Ammeter is always connected in series with appliance. A galvanometer can be converted into an ammeter by connecting a very low resistance called (shunt S) in parallel with galvanometer. Since, Potential difference across Galvanometer

## Moving Coil Galvanometer

Chapter-4|Moving Charges and Magnetism| NCERT 12th Physics: Moving Coil Galvanometer: Galvanometer is used for detecting and measuring small electric currents. Principle: Its working is based on the fact that when a current carrying coil is placed in a magnetic field, it experiences a torque. Construction: The moving coil galvanometer consists of a coil with a

## Torque On a Current Loop In a Uniform Magnetic Field (Magnetic Dipole)

Chapter-4|Moving Charges and Magnetism| NCERT 12th Physics: Torque On a Current Loop In a Uniform Magnetic Field (Magnetic Dipole): Let we consider a rectangular loop ABCD be suspended in a uniform magnetic field B. Let AB=CD=b and AD=BC=a and I be the current flowing through the loop. Case-1:The rectangular loop is placed such that the

## Magnetic Dipole Moment of a Revolving Electron (For Hydrogen Like Atom)

Chapter-4|Moving Charges and Magnetism| NCERT 12th Physics: Magnetic Dipole Moment of a Revolving Electron (For Hydrogen Like Atom): Let an electron(e⁻) is revolving in a loop(atom), mass m, velocity v and radius r. When electron (e⁻) revolve around nucleus, it constitute a current. Since,  q= It, therefore I= q/t = e⁻/t.       This

## Circular Current Loop as a Magnetic Dipole

Chapter-4|Moving Charges and Magnetism| NCERT 12th Physics: Circular Current Loop as a Magnetic Dipole: Main Topic: A current loop behaves as a magnetic dipole Magnetic field lines are always from South(S) to North(N). If we look at the upper face, current is showing  clockwise, so it has South polarity. If we look at lower face

## Force Between Two Parallel Current Carrying Conductors

Chapter-4|Moving Charges and Magnetism| NCERT 12th Physics: Force Between Two Parallel Current Carrying Conductors: Let we consider two parallel infinite long straight conductors.     Note: Two linear parallel conductors carrying current in the same direction attract each other, while carrying in opposite direction they repel to each other.     Definition of Ampere:

## Magnetic Force on a Current Carrying Conductor In a Uniform Magnetic Field

Chapter-4|Moving Charges and Magnetism| NCERT 12th Physics: Magnetic Force on a Current Carrying Conductor (In a Uniform Magnetic Field): We know that a moving charge particle experiences a magnetic force in a magnetic field and the value of force is F= q(V×B). A current carrying wire has a chargers moving inside it opposite direction of

## Cyclotron

Chapter-4|Moving Charges and Magnetism| NCERT 12th Physics: Cyclotron: It is device used to accelerate charged particle like proton and alpha-particle etc. to very high energies. It was invented by E.O. Lawrence and M.S Livingston in 1934. Principle: A charged particle can be accelerated to very high energy by making it pass through a moderate electric

## Force on a Moving Charge in a Uniform Magnetic and Electric Field (Lorentz Force)

Chapter-4|Moving Charges and Magnetism| NCERT 12th Physics: Force on a Moving Charge in a Uniform Magnetic and Electric Field (Lorentz Force):   When we combine these two forces then we find Lorentz Force, If we adjust the value of E and B such that magnitude of two forces are equal and opposite in direction then

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