Answer:
The radius is 
Explanation:
From the question we are told that
The magnetic field is 
The electron kinetic energy is 
Generally for the collision to occur the centripetal force of the electron in it orbit is equal to the magnetic force applied
This is mathematically represented as
=> 
Where m is the mass of electron with values 
v is the escape velocity which is mathematically represented as
So
apply indices
substituting values
Answer:
Explanation:
Assuming uniform spread of sound with no significant reflections or absorption. We know that sound intensity varies 
where r is the distance
Since intensity is given then when at 3 m
Since we have the constant then at 4m
Intensity, 
Answer:
The value is 
Explanation:
From the we are told that
The radius of the sphere is 
The temperature is 
The average temperature of the rest of the universe is 
Generally the change in entropy of the entire universe per second is mathematically represented as
Here 
is the entropy of the rest of the universe which is mathematically represented as
Here Q is the quantity of heat radiated by the star which is mathematically represented as
Here 
is the Stefan-Boltzmann constant with value
=> 
=> 
So
=> 
Here 
is the entropy of the rest of the universe which is mathematically represented as
=> 
=> 
So
=>
Answer:
Explanation:
A) When a dipole is placed in an electric field , it experiences a torque equal to the following
torque = p x E = p E sinθ , where θ is angle between direction of p and E .
It will be zero if θ = 0
or if both p and E are oriented in the same direction.
It is the stable orientation of dipole.
If θ = 180° ,
Torque = 0
In this case both p and E are oriented in opposite direction .
It is the unstable orientation of the dipole because if we deflect the dipole by even small angle , it goes back to most stable orientation due to torque acting on it by electric field.
Answer:
Explanation:
Calculate the volume of the lead
Now calculate the bouyant force acting on the lead
This force will act in upward direction
Gravitational force on the lead due to its mass will act in downward direction
Hence the difference of this two force
If V is the volume submerged in the water then bouyant force on the bobber is
Equate bouyant force with the tension and gravitational force
Now Total volume of bobble is
=
