# Induced Emf in a Rectangular Coil

• member 217843
In summary, the conversation discusses the calculation of the average emf induced in a rectangular coil that is rotated in a uniform magnetic field. After calculating the change in flux and using the formula for emf, the participant's answer of -4.34 V was initially marked incorrect, but was later corrected by the online homework site.
member 217843

## Homework Statement

A rectangular coil of 90 turns has dimensions of 22 x 65 cm and is located in a uniform 1 T magnetic field. In 1.7 s, the plane of the coil is rotated from a position where it makes an angle of 19° with the magnetic field to a position where it makes an angle of 64°. Calculate the average emf induced in the coil.

## Homework Equations

emf= -N*(d$\Phi$/dt)
$\Phi$=BAcos$\vartheta$

## The Attempt at a Solution

So I calculated the change in flux to be: (B*A*cos(90-64))-(B*A*cos(90-19)=B*A*(cos(26)-cos(71))

I then calculated emf.
emf= - ((90 turns)*(1 T)*(0.22m*0.65m)*(cos(26)-cos(71)))/1.7 s = -4.34 V
This is wrong. I then entered the absolute value, which is also incorrect.

Hi SgtMousse!
SgtMousse said:
I then calculated emf.
emf= - ((90 turns)*(1 T)*(0.22m*0.65m)*(cos(26)-cos(71)))/1.7 s = -4.34 V
This is wrong. I then entered the absolute value, which is also incorrect.

looks ok

have you tried 4.3 V, since it should be two significant figures ?​

Apparently my answer was correct, even though it was marked wrong. I just checked my online homework site, and they marked it correct. They must have had it wrong before. Thanks anyway!

## What is induced emf?

Induced emf, or electromotive force, is the voltage generated in a conductor or coil when it moves through a magnetic field or when there is a change in the magnetic field passing through the conductor or coil.

## How is induced emf calculated in a rectangular coil?

The induced emf in a rectangular coil can be calculated using the equation E = -N(dΦ/dt), where E is the induced emf, N is the number of turns in the coil, and dΦ/dt is the rate of change of magnetic flux through the coil.

## What factors affect the magnitude of induced emf in a rectangular coil?

The magnitude of induced emf in a rectangular coil is affected by the strength of the magnetic field, the number of turns in the coil, the area of the coil, and the rate of change of magnetic flux through the coil.

## What is the direction of induced emf in a rectangular coil?

The direction of induced emf in a rectangular coil is determined by the direction of the magnetic field and the direction of change in magnetic flux. It follows the right-hand rule, where the thumb points in the direction of the magnetic field and the fingers curl in the direction of the induced current.

## How is induced emf used in practical applications?

Induced emf is used in various practical applications, such as generators, transformers, and motors, to convert mechanical energy into electrical energy or vice versa. It is also used in devices like magnetic sensors and electromagnetic brakes.

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