A 18.5-cm-diameter loop of wire is initially oriented perpendicular to a 1.3-T magnetic field. The loop is rotated so that its plane is parallel to the field direction in 0.18 s . What is the average induced emf in the loop? Express your answer to two significant figures and include the appropriate units.

0.2v

Explanation:

Data given,

Diameter=18.5cm

Hence we can calculate the radius as D/2=18.5/2=9.25cm

radius=9.25cm/100=0.0925m

The area is calculated as

magnetic field, B=1.3T

time,t=0.18s

The flux is expressed as

since the loop is parallel, the angle is 0

Hence we can calculate the flux as

to determine the emf induced in the loop, we use Faraday law

Note the voltage is not negative but the negative sign shows the current flows in other to oppose the flux

air exerts forces on falling objects near earth’s surface.

explanation:

the term 'free falls' refer to object that are falling towards the earth, in a situation in which gravity is the only force acting on the object.

for an object in free fall, the acceleration is constant (g, the gravitational acceleration), and so the velocity of the object constantly increases.

for objects near earth's surface, there is always another force acting on the object: the resistance due to the air. this force is opposed to the direction of fall of the object, and it is proportional to the velocity of the object, so as the object falls down, this force increases up to a point when it balances the force of gravity, and the object continues its motion at constant velocity (called terminal velocity). since in this case gravity is not the only force acting on the object, we are not in a situation of free fall.