Answer:
Please refer to the figure.
Explanation:
The crucial point here is to calculate the enclosed current. If the current I is flowing through the whole cross-sectional area of the wire, the current density is
The current density is constant for different parts of the wire. This idea is similar to that of the density of a glass of water is equal to the density of a whole bucket of water.
So,
This enclosed current is now to be used in Ampere’s Law.
Here, 
represents the circular path of radius r. So we can replace the integral with the circumference of the path, 
.
As a result, the magnetic field is
The photoelectric emission is possible if the wavelength of the incident light is less than that of yellow light
Answer:
The mantle exists above the crust of the earth
According to the Bernoulli's equation,the pressure difference between the wide and narrow ends of the pipe is given by
Here, 
is the velocity of water through wide ends of cylindrical pipe and 
is the velocity of water through narrow ends of cylindrical pipe.
Given, 
Now from equation continuity,
.
Here, 
and 
are cross- sectional areas of wide and narrow ends of cylindrical pipe.
As pipe is circular, so
.
At the second point, the diameter is halved, which means the radius is also halved. Therefore,
Substituting these values with the density of water is 
in pressure difference formula we get.
