Answer:
B. Maximum velocity of ejected electrons.
Explanation:
The ejection of electrons form a metal surface when the metal surface is exposed to a monochromatic electromagnetic wave of sufficiently short wavelength or higher frequency (or equivalently, above a threshold frequency), which leads to the enough energy of the wave to incident and get absorbed to the exposed surface emits electrons. This phenomenon is known as the photoelectric effect or photo-emission.
The minimum amount of energy required by a metal surface to eject an electron from its surface is called work function of metal surface.
The electrons thus emitted are called photo-electrons.
The current produced as a result is called photo electricity.
Energy of photon is given by:

where:
h = Planck's constant
frequency of the incident radiation.
Answer:
rpm
Explanation:
Given that rotational kinetic energy = 
Mass of the fly wheel (m) = 19.7 kg
Radius of the fly wheel (r) = 0.351 m
Moment of inertia (I) = 
Rotational K.E is illustrated as 





Since 1 rpm = 



Answer:
Difference in temperature
Contact between the bodies
Answer:
Final speed of striped ball is 3 m/s in left direction .
Explanation:
Given :
Two billiard ball with the same mass moves toward the left at the same speed 3 m/s .
Let , us assume right hand side direction to be positive and left hand side direction to be negative .
Also , let speed of ball after collision is (striped ball ) u and (solid ball) v .
It is also given that the collision is elastic .
Therefore , kinetic energy is conserved .
...... ( 1 )
Also , by conserving linear momentum .
We get :
...... ( 2 )
Putting value of u from equation 2 to equation 1 .
We get :

And , u = -3 m/s .
Therefore , final speed of striped ball is 3 m/s in left direction .
Hence , this is the required solution .