Answer:
Approximately 0.0898 W/m².
Explanation:
The intensity of light measures the power that the light delivers per unit area.
The source in this question delivers a constant power of 
. If the source here is a point source, that of power will be spread out evenly over a spherical surface that is centered at the point source. In this case, the radius of the surface will be 9.6 meters.
The surface area of a sphere of radius 
is equal to 
. For the imaginary 9.6-meter sphere here, the surface area will be:
.
That power is spread out evenly over this 9.6-meter sphere. The power delivered per unit area will be:
.
Answer:
Refraction
Explanation:
When light passes from a rarer medium into a denser medium, it bends in the medium away from the normal. This creates the phenomenon of "apparent depth" as given in the question.
Answer:
Explanation:
a )
hear energy required to melt 1 g of ice = 340 J ,
hear energy required to melt 80 g of ice = 340 x 80 J = 27220 J .
b ) energy gained by the melted ice ( water at O°C ) = m ct
where m is mass of water , s is specific heat and t is rise in temperature
= 80 x 4.2 x ( 8°C - 0°C)
= 2688 J .
c )
energy lost by lime juice = energy gained by ice and water
= 27220 J + 2688 J .
= 29908 J .
d )
Let specific heat required be S
Heat lost by lime juice = M S T
M is mass of lime juice , S is specific heat , T is decrease in temperature
= 320 g x S x ( 29 - 8 )°C
= 6720 S
For equilibrium
Heat lost = heat gained
6720 S = 29908 J
S = 4.45 J /g °C .
Answer:
Electromagnetic force
Explanation:
There are four fundamental forces in nature:
- Gravity: it is the force that is exerted between any objects with mass. It is the weakest of all forces, so it is only relevant at planetary scales. It is always attractive, and it has an infinite range.
- Electromagnetic force: it is the force exerted between charged objects and between magnets (it is responsible for electric fields and magnetic fields). It is the 2nd strongest force, and it is the force that holds atoms in a molecule together. It can be attractive or repulsive, and it has an infinite range.
- Strong nuclear force: it is the strongest of all forces. It is responsible for holding the nucleons together inside the nucleus, and it is attractive. It has a very limited range (
), so it is relevant only at very small scales
- Weak nuclear force: it is the force responsible for radioactive decays and neutrino interactions. It also has a very short range (
Looking at all these definitions, we see that the term that defines the force that acts between charged particles is the electromagnetic force.
