To develop this problem it is necessary to apply the concept of Frequency based on speed and wavelength.
According to the definition the frequency can be expressed as

Where,
v = Velocity
Wavelength
Our value are given by,
v = 345m/s

Replacing


Therefore the frequency of the tuning fork is 547.61Hz
Answer:
(a). Index of refraction are
= 1.344 &
= 1.406
(b). The velocity of red light in the glass
2.23 ×
The velocity of violet light in the glass
2.13 ×
Explanation:
We know that
Law of reflection is

Here
= angle of incidence
= angle of refraction
(a). For red light
1 ×
=
× 
= 1.344
For violet light
1 ×
=
× 
= 1.406
(b). Index of refraction is given by

= 1.344


2.23 ×
This is the velocity of red light in the glass.
The velocity of violet light in the glass is given by

2.13 ×
This is the velocity of violet light in the glass.
<span>The correct answer is C) a motor.
In particular, we are talking about an AC motor, which produces an alternating current. In an AC motor, a coil is immersed in a rotating magnetic field. Due to the motion of the magnetic field,the angle between the direction of the field and the surface enclosed by the coil changes. As a result, the magnetic flux through the coil changes over time (the magnetic flux is given by:
</span>

<span>
where B is the intensity of the magnetic field, A is the area enclosed by the coil and </span>

<span> is the angle between the direction of B and the perpendicular to the plane of the coil). For Faraday-Newmann-Lenz law, this change in flux induces an electromotive force (emf) into the coil, according to:
</span>

<span>
where the numerator is the variation of magnetic flux and dt is the time interval. This emf in the coil produced an electrical current in the circuit.</span>