Answer:
6.0 ×
W/
Explanation:
From Wien's displacement formula;
Q = e A
Where: Q is the quantity of heat transferred, e is the emissivity of the surface, A is the area, and T is the temperature.
The emissive intensity =
= e
Given from the question that: e = 0.6 and T = 1000K, thus;
emissive intensity = 0.6 × 
= 0.6 × 1.0 × 
= 6.0 ×

Therefore, the emissive intensity coming out of the surface is 6.0 ×
W/
.
Answer:


Explanation:
Wave 1, 
Wave 2, 
Wave 3, 
Wave 4, 
The general equation of travelling wave is given by :

The value of
will remain the same if we take phase difference into account.
For first wave,



For second wave,



For the third wave,



For the fourth wave,



It is clear from above calculations that waves 1 and 3 have same time period. Also, wave 2 and 4 have same time period. Hence, this is the required solution.
Answer:
Magnification m is 2.5cm
Explanation:
This problem bothers on lenses
Given data
Object distance u= 4cm
Height of object v= 10 cm
The problem is quite straightforward seeing that object and image distances are given
We know that the magnification
m= size of image/size of object
m= v/u= 10/4 = 2. 5cm
What is a convex lens
A convex lens is a type of lens that has the centre thicker than the ends, the thickness at the centre makes the lens surface to curve outward. Convex lens causes close light rays of light to converge at a point after refraction.
The artic tundra can be found in D. All of the above.
Electromagnetic spectrum
Radio waves
Micro waves
Infrared
Visible lighta
ultraviolet
x ray
gammary