The intensity is defined as the ratio between the power emitted by the source and the area through which the power is calculated:

(1)
where
P is the power
A is the area
In our problem, the intensity is

. At a distance of r=6.0 m from the source, the area intercepted by the radiation (which propagates in all directions) is equal to the area of a sphere of radius r, so:

And so if we re-arrange (1) we find the power emitted by the source:
Answer:
There will be no change in the direction of the electric field .
Explanation:
The direction will remain the same because the sign of the charges has no effect on it.
When one replaces the conducting cube with one that has positive charge carriers there will be no change in the direction of the field as there is no defined relationship between the direction of the electric field and sign of the charge.
Answer:

Explanation:
Given:
radius of capillary, 
angle of contact, 
density of water, 
surface tension of water, 
height, h = ?
We have the equation for the height of meniscus as:



No, the capillary action alone cannot be the mechanism of water transportation to the top of the trees. Transpiration also creates a suction pressure in the xylem complementary to the ascent of sap and cohesion of water being the other causes of movement of water up in the plants.
Answer:0
Explanation:
Given
circumference of circle is 2 m
Tension in the string 


In this case Force applied i.e. Tension is Perpendicular to the Displacement therefore angle between Tension and displacement is 



Answer:
The astronaut who has a mass of 80 kg without the toolkit do survive with 40 seconds of remaining air
Explanation:
Due the astronaut throws the 10-kg tool kit away with a speed of 8 m/s, it gives a momentum equivalent but in the other direction, so
, then we can find the speed that the astronaut reaches due to its weight we get,
.
Finally, as the distance to the space shuttle is 200m, the time taken to the astronaut to reach it at the given speed will be
, as the remaining air time is 4 min or 240 seconds, The astronaut who has a mass of 80 kg without the toolkit do survive with 40 seconds of remaining air.