Explanation:
Given that,
Length of gold wire, l = 4 m
Voltage of battery, V = 1.5 V
Current, I = 4 mA
The resistivity of gold, 
Resistance in terms of resistivity is given by :

Also, V = IR
So,

A is area of wire,
, r is radius, r = d/2 (diameter=d)

Out of four option, near option is (C) 17 μm.
<h2>
Option 1 is the correct answer.</h2>
Explanation:
Power of heater, P = 1790 W
Time used, t = 24 hours = 24 x 60 x 60 = 24 x 3600 s
We have the equation

We need to find energy,
Substituting

Energy = 1790 x 24 x 3600 J
Option 1 is the correct answer.
Answer:
34.5 m
Explanation:
Given data : An elephant produces 10 Hz sound wave. Assuming the speed of sound in air is 345 m/s. To find : What is the wavelength of sound ? Answer : The wavelength of the sound is 34.5 m.
Answer:
True
Explanation:
Johannes Kepler was a German astronomer, mathematician and astrologer. He proposed a model of the solar system which remains in use, with some modifications. Moreover, he developed the laws of planetary motion which explain how the planets move around the sun. This work was not only significant on its own, but it also provided the foundations for Newton's theory of universal gravitation.
Answer:
d) v1 = v2 = v3
Explanation:
This can be answered using conservation of energy. We calculate the mechanical energy E=K+U (sum of kinetic and gravitational potential energies) at the original and final points, and impose they are equal.
At the original point we have, for the three balls:

At the final point we have, for the three balls:

Since we have
, and
is the same for all balls, then
is the same for all balls, which means that
, the final velocity, is the same for all balls.