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:
Sound waves are produced when something vibrates.
Explanation:
The vibrating body causes the medium (water, air, etc.) Vibrations in air are called traveling longitudinal waves, which we can hear. Sound waves consist of areas of high and low pressure called compressions and rarefactions, respectively.
Sorry if this if wrong
Boiling water is a common method used to sterilize water that may be contaminated. subjecting microbes to such high temperatures is an example of a(n) microbicidal technique.
A substance that eliminates microorganisms (such as bacteria) is known as microbicide and the techniques that involve destruction of microbes are known as microbicidal techniques.
The pathogen biofilm was effectively destroyed by the combined microbicidal effects of hot water (50, 60, or 70 °C) and 2% citric acid. It was discovered that the combination of hot water and citric acid caused sub-lethally harmed cells.
A fairly easy way to disinfect water is to boil it. The majority of dangerous organisms, notably viruses and bacteria that cause waterborne infections, are killed when water is heated to a high temperature of 100°C. The water must boil for at least 20 minutes in order to be most effective.
Hence, water that may be polluted is frequently sterilized by boiling. Using such high temperatures to kill germs is an example of a microbicidal method.
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The cost of boiling 500cm3 of water using the 3kW kettle is 1.35 P.
<h3>
Cost of electricity for 3 kW kettle</h3>
The cost is calculated as follows;
1 unit = 9p /kWh
Total energy consumed by 3 kW kettle, E = P x t
where;
- P is power (kW)
- t is time in (hr)
E = 3 kW x (3 mins/60 mins/hr)
E = 0.15 kWh
Energy cost = 9 p/kWh x 0.15 kWh = 1.35 P
Thus, the cost of boiling 500cm3 of water using the 3kW kettle is 1.35 P.
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I believe the answer is D. Have a good day.