Answer:
Absolute refractive index is 1
Relative refractive index is lesser than 1.
Explanation:
Answer:
D
Explanation:
the total speed and the total mass of the entire system remain the same weather one object is moving or stationary.
When two or more objects collide, the collision does not change the
total momentum of the two objects.
Whatever momentum is lost by one object in the collision is gained
by the other. The total momentum of the system is conserved.
Answer:
Explanation:
We shall solve this problem on the basis of averaging , otherwise it will require integration which is a complex operation .
According to newton's law of cooling
dQ / dt = k ( T₁ - T₂ )
T₁ is temperature of surrounding and T₂ is temperature of object .
For the heating by 2 degree
dQ = ms x ΔT , m is mass , s is specific heat and ΔT is rise of
= ms x 2
dt = 1 second
T₁ the average temperature of object = (30 + 32) / 2 = 31
dQ = ms x ΔT
ms x 2 = k ( 100 - 31 )
k = 2 ms / 69
In the second case bar's temperature rises from 32 to 70
average temperature = 32 + 70 / 2 = 51
If t be the time required
dQ = ms x ( 70 - 32 ) = 38ms
38ms / t = k ( 100 - 51 )
38ms / t = (2ms / 69) x 49
t = 38 x 69 / (2 x 49)
= 26.75 s .
Answer: 
Explanation:
Given
Current in the first wire 
Current in the second wire 
wires are 
apart
Force per unit length between the current-carrying wires is
Force exerted by the wires is the same
Put the values
This force will be repulsive in nature as the current is flowing opposite
Echolocation. It’s the process of using sound waves to locate objects, like it’s name suggests.
