1 Physics -- Electromagnetic Induction

The cores of inductive devices like the choke, the dynamo or the transformer are laminated. Why?

1 Answers

When AC current flows through the coil of an inductive device, eddy currents are set up in its core. The eddy currents have heating effect. If the core is a single piece of metal, its resistance becomes very low and very high eddy current flows through it. This causes excessive heating of the core and may destroy the device. To avoid destruction by heating, the eddy currents are to be greatly reduced. To reduce the eddy currents, the resistance of the core is to be increased significantly for which the insulated lamina are used.

How can VL or VC be greater than V in a series LCR circuit?

At resonance, V_L and V_C are in antiphase (i.e. 180⁰ out of phase), therefore, their vector sum can be quite small— zero They are equal in magnitude at resonance.

So, they are greater than V in series LCR circuit.

For very high frequency a.c. supply, a capacitor behaves like a pure conductor. Why?

Describe Hall Effect along with its derivation .

The Hall Effect, also called the Hall–Heroult effect, is the influence of the transverse component of an electric current on the magnetic field in a transverse Hall bar. When a current flows in a plane perpendicular to the direction of the magnetic field, the Lorentz force acts on the magnetic charges (magnetic flux) enclosed by the transverse current.

The Lorentz force is the force experienced by a magnetic charge when acted upon by an external force field, which in this case is the...

A coil of wire containing 500 circular loops with radius 4.00 cm is placed between the poles of a large electromagnet, where the magnetic field is uniform and at an angle of 60° with the plane of t...

Why can't a transformer be used to change the value of DC voltage?

A transformer relies on the principle of electromagnetic induction, which works with changing magnetic fields. Since direct current (DC) has a constant magnitude and does not change direction, it does not create the varying magnetic field necessary for induction in a transformer. Therefore, transformers are not suitable for altering the value of DC voltage.

Two closely wound circular coils have the same number of turns , but one has twice the radius of the other . What is the ratio of self inductances of the two coils ?

The self-inductance of a coil is given by the formula:

L = (μ * N² * A) / l,

where L is the self-inductance, μ is the permeability of free space (constant), N is the number of turns, A is the cross-sectional area of the coil, and l is the length of the coil.

Let's assume the smaller coil has a radius 'r' and the larger coil has a radius '2r' (twice the radius of the smaller coil). Since the number of turns is the same for both coils, let's denote it as 'N' for simplicity.

For the smaller coil:

A =...

A coil of wire of certain radius has 600 turns and a self inductance of 108mH . What will be the self inductance of another similar coul with 500 turns ?

State the rule used to determine the direction of current induced in a conductor moving in a perpendicular magnetic field .

The rule used to determine the direction of the current induced in a conductor moving in a perpendicular magnetic field is known as Fleming's right-hand rule. According to this rule:

1. Extend your thumb, index finger, and middle finger of your right hand perpendicular to each other.

2. If the thumb points in the direction of motion of the conductor (conventional current flow), the index finger points in the direction of the magnetic field, then the middle finger will point in the direction of...

Describe mutual induction and write their uses .

Mutual induction is a phenomenon where a changing magnetic field in one coil induces a voltage in a nearby coil. It is utilized in various applications:

1. Transformers: Mutual induction is the basis of transformers, which are used to step up or step down voltages in electrical power transmission and distribution systems.

2. Inductive Coupling: Mutual induction enables wireless power transfer, RFID systems, and near-field communication, where energy or information is transferred between two...

Write short notes about induction break .

1.Induction Brake Basics: An induction brake, also known as regenerative braking, harnesses the electric motor's ability to act as a generator. When the driver applies the brakes, the electric motor switches its function from propulsion to generation, converting the kinetic energy of the vehicle into electrical energy.

2. Energy Conversion: During induction braking, the rotating wheels drive the motor, causing it to generate electricity. This electrical energy is then fed back into the...

Calculate the induced EMF in 100cm2 circular coil having 100 turns , when the coil is taken to the magnetic field of flux density 0.1 T in 0.1 sec .

A vertical magnetic field is perpendicular to the horizontal plane of a wire loop. When the loop is rotated about a horizontal axis in the plane, the current induced in the loop reverses direction ...

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