Answer:
a. 12 m/s² down
Explanation:
Acceleration has units of length per time squared. Acceleration is a vector, so it also has a direction.
The frequency of the radio station is

For radio waves (which are electromagnetic waves), the relationship between frequency f and wavelength

is

where c is the speed of light. Substituting the frequency of the radio station, we find the wavelength:
In technical terms, every coil of wire increases the "magnetic flux density" (strength) of your magnet.
So it's A (magnetic field increase)
Answer:
emf induced is 0.005445 V and direction is clockwise because we can see area is decrease and so that flux also decrease so using right hand rule direction of current here clockwise
Explanation:
Given data
initial circumference = 165 cm
rate = 12.0 cm/s
magnitude = 0.500 T
tome = 9 sec
to find out
emf induced and direction
solution
we know emf in loop is - d∅/dt ........1
here ∅ = ( BAcosθ)
so we say angle is zero degree and magnetic filed is uniform here so that
emf = - d ( BAcos0) /dt
emf = - B dA /dt ..............2
so area will be
dA/dt = d(πr²) / dt
dA/dt = 2πr dr/dt
we know 2πr = c,
r = c/2π = 165 / 2π
r = 26.27 cm
c is circumference so from equation 2
emf = - B 2πr dr/dt ................3
and
here we find rate of change of radius that is
dr/dt = 12/2π = 1.91
cm/s
so when 9.0s have passed that radius of coil = 26.27 - 191 (9)
radius = 9.08
cm
so now from equation 3 we find emf
emf = - (0.500 ) 2π(9.08
) 1.91 
emf = - 0.005445
and magnitude of emf = 0.005445 V
so
emf induced is 0.005445 V and direction is clockwise because we can see area is decrease and so that flux also decrease so using right hand rule direction of current here clockwise
The coil is rotated rapidly in the magnetic field.
The magnetic flux linked with the coil changes and thus, an emf is induced which leads to the flow of current .
when the coil rotates and is in a position along the direction of the magnetic field, emf is maximum while when it is perpendicular to the magnetic field,emf is 0.
Thus an ac generator converts mechanical to electrical energy.It works on the principle of electromagnetic induction. The polarity at the supply terminals changes like.. 100 times a second if the frequency is 50 Hz(50 times+ and 50 times - )
hope it helps!