Answer:
The value is 
Explanation:
From the question we are told that
The length of the wire is 
The current density is 
The conductivity is
Generally conductivity is mathematically represented as

Here R is the resistance which is mathematically represented as

Here I is the current which is mathematically represented as

So

And

=> 
=> 
=> 
=> 
Question four bulbs A,B,C and D are connected in a circuit shown in the figure below, the letters X, Y and Z represent three switches. Which switch is used to operate switch A separately?
Answer: x
Answer:
50 kg
Explanation:
Given,
Force ( F ) = 100 N
Acceleration ( a ) = 2 m/s^2
To find : Mass ( m ) = ?
Formula : -
F = ma
m = F / a
= 100 / 2
m = 50 kg
Therefore, the mass of the object is 50 kg.
Answer:
32.76 Volt
Explanation:
frequency, f = 400 Hz
Area of crossection, A = 13 cm²
Maximum flux density, B = 0.9 tesla
Number of turns in secondary coil, N = 70
Let the maximum induced voltage is e.
According to the Faraday's law of electromagnetic induction, the induced emf is equal to the rate of change of magnetic flux.
e = dФ/dt

Time is defined as the reciprocal of frequency.
So, e = N B A f
e = 70 x 0.9 x 13 x 10^-4 x 400
e = 32.76 volt
Almost all of the energy on Earth comes from the Sun
The energy in fossil fuels originally came from the Sun
Plants convert the energy
Explanation:
The sun is the ultimate source of energy on earth and even the whole of the solar system. The sun drives and powers all external processes on earth. It produces its energy from the nuclear fusion of lighter nuclei into heavier ones.
- Almost all of the energy on earth comes from the sun. A few component of the energy on the surface comes from the internal heat engine.
- The energy of fossil fuels originally came from the sun. This is because, plants stores the energy in the process of photosynthesis. When they die and the energy is not released, the energy is stored as fossil fuels.
- Plants in the process of photosynthesis converts the energy. Here green plants combines carbon dioxide and water in the presence of sunlight.
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