A coil of wire is arranged with its plane perpendicular to a uniform magnetic field with flux density B. When the radius of the coil increases from r₁ to r₂ in time At, then what is the emf induced in the coil?
Correct answer: A. πB(r2-r2)/Δt
- A. πB(r2-r2)/Δt
- B. πB(r2-r2)2/Δt
- C. B(r2-r2)/Δt
- D. B(r2+r2)/Δt
Explanation
The induced electromotive force (EMF) in a coil with a changing area in a magnetic field is given by Faraday's law as EMF =- Δ/Δt.where Δ is the change in magnetic flux. The magnetic flux (4) through the coil is given by B. A, where B is the magnetic flux density, and A is the area of the coil.The area of the coil is proportional to r² (assuming a circular coil), so the change in area AA when the radius changes from r₁ to rais (rri).Therefore, the induced EMF (EMF) is given by:EMF - Δ/Δt = - BΔA/Δt = πB(r2-r2)/ΔtTherefore, the correct option is (a))πB(r2-r2)/Δt
Report an error
The more specific you are, the faster it gets fixed. A source beats an opinion.
Prefer email? [email protected]
About Electromagnetism
Magnetic flux density and magnetic flux describe the strength of a magnetic field and the field passing through a surface. A charged particle moving through a magnetic field experiences a force perpendicular to its velocity and may follow circular or helical motion, depending on the angle between velocity and field.
Practise Electromagnetism
1,176 free Electromagnetism MCQs from Physics, each with the correct answer and an explanation. Unlimited attempts, no account needed.
Discussion
Stuck on an option, or know a faster way to get there? Ask or explain it here.
No comments yet. Be the first to explain this one.
Exams that ask Physics questions like this
Physics is on 16 papers prepared for on TestUstad, and all of them draw the same bank, so this question is worth knowing for every one of them.
More Electromagnetism questions
When the motor is at its maximum speed, then back electromotive force (emf) will be
Transformer works on the principle of
An electric current induced within the body of a conductor when that conductor either moves through a non-uniform magnetic field or in a region where there is a change in magnetic flux is called
The emf induced in a conductor of unit length moving with unit velocity at right angies to a magnetic field is equal to Ivey
Self inductance of a long solenoid is
A step up transformer has transformation ratio of 3:2. what is the voltage in secondary if the primary voltage is 30V.