Answer:
Therefore the ratio of diameter of the copper to that of the tungsten is

Explanation:
Resistance: Resistance is defined to the ratio of voltage to the electricity.
The resistance of a wire is
- directly proportional to its length i.e

- inversely proportional to its cross section area i.e

Therefore

ρ is the resistivity.
The unit of resistance is ohm (Ω).
The resistivity of copper(ρ₁) is 1.68×10⁻⁸ ohm-m
The resistivity of tungsten(ρ₂) is 5.6×10⁻⁸ ohm-m
For copper:


......(1)
Again for tungsten:

........(2)
Given that
and 
Dividing the equation (1) and (2)

[since
and
]



Therefore the ratio of diameter of the copper to that of the tungsten is

Answer:

Explanation:
Using Kepler's third law, we can relate the orbital periods of the planets and their average distances from the Sun, as follows:

Where
and
are the orbital periods of Mercury and Earth respectively. We have
and
. Replacing this and solving for

Kinetic energy means fast move movement
The two points on a periodic wave in a medium are said to be in phase if they have the same amplitude and are moving in the same direction.
Option 4.
Explanation:
A periodic wave is termed for waves which flow in a repetition pattern in a given time scale. Periodic wave can also be termed as a transverse wave. So a transverse wave have various crests and troughs. The two successive crests and two successive troughs are said to be in phase with each other.
Thus, for a periodic wave in a medium, the in phase can be obtained in two points which have the same amplitude and are moving in the same direction.
As amplitude is a scalar quantity and so direction should be taken into consideration for making the points related to successive crests only in phase with themselves. Also this also relates the points related to successive troughs to be in phase with each other. But a crest and a trough will not be in phase with each other.
Thus, option 4, that is the two points on a periodic wave in a medium are said to be in phase if they have the same amplitude and are moving in the same direction.