A 147 turn circular coil of radius 2.49 cm is immersed in a uniform magnetic field that is perpendicular to the plane of the coil. Over an interval of 0.183 s , the magnetic field strength increases from 53.5 mT to 95.9 mT . Find the magnitude of the average emf E avg induced in the coil during this time interval, in millivolts.

Explanation:

Given that

Number of turn is 147

N=147

Radius of coil is r=2.49cm

r=0.0249m

Time interval t=0.183s

Magnetic field increase from

T1=53.5mT to T2=95.9mT

The EMF of magnetic field is given as, using Faraday law of induction

EMF= -NA∆B/∆t

Area of the coil circular is given as

A=πr²

A=π×0.0249² = 1.948×10^-3m²

Then,

EMF=-147×1.948×10^-3×(95.9×10^-3 - 53.5×10^-3) / 0.183

EMF=-0.28633(0.0424) / 0.183

EMF=-0.06634 Volts

Then, EMF=-66.34 mV

Then, the magnitude is

|EMF|= 66.34 milliVolts

The answer is B
A decreased wavelength means higher pitch
Higher wavelength means lower pitch.
Think about an airplane. It makes noise and flies towards you, so you hear a higher pitch. As soon as it passes you, you hear a neeew. Changing from the high pitch to a lower pitch