Answer:
The distance of the object placed on the principal axis from the concave mirror.
Explanation:
In a concave mirror, the nature of the image formed formed by the object placed in front of the mirror depends on the position of the object placed in from of the mirror. It all depends on the distance between the mirror and the object placed on the principal axis.
The closer the object is to the lens, the more larger or magnified the image formed will be. For example an object placed between the focal point and the pole of a concave produces a much larger image than an object placed beyond the centre of curvature of such mirror.
To solve this problem we will apply the concepts related to the Magnetic Force, this is given by the product between the current, the body length, the magnetic field and the angle between the force and the magnetic field, mathematically that is,

Here,
I = Current
L = Length
B = Magnetic Field
= Angle between Force and Magnetic Field
But 

Rearranging to find the Magnetic Field,

Here the force per unit length,

Replacing with our values,


Therefore the magnitude of the magnetic field in the region through which the current passes is 0.0078T
Answer:
This is due to a relative decrease in atmospheric pressure in high places.
Explanation:
Given that atmospheric pressure decreases at the higher point or ground, this reduced atmospheric pressure, however, will be unable to contain the Mercury in the barometer tube.
Therefore, at the top of the mountain where the air pressure is low, the barometer reading ultimately goes down.
Hence, the level of mercury falls in a barometer while taking it to a mountain "due to a relative decrease in atmospheric pressure in high places."
Answer:

Explanation:
The velocity v₁ can be calculated with the kinematic formula:

Since the object is initially at rest, v₁ becomes:

Where g is the acceleration due to gravity. Now, the velocity v₂ can be calculated with the same formula, but now the initial velocity is v₁:

Substituting v₁ in this expression and solving for v₂, we get:

Now, dividing v₂ over v₁, we get the expression:

It means that v₂ is √2 times v₁.