According to classical model of light, why should the photo current increase on increasing intensity?
According to classical model of light, why should the photo current increase on increasing intensity?
The correct option is B The number of electrons being ejected out has increased as electrons now receive higher energy and thus even after losing energy in collisions, have sufficient left to overcome the work function and come out.
Imagine there is a wall and there are 8 balls that you need to throw over to the other side.
Say, it’s given that the minimum energy required by a ball to cross over the wall is 5J, and in each collision a ball loses 2J of energy.
Let’s look at how some of the balls undergo collisions with the neighboring balls and lose energy, and record our observations as follows.
Balls 1 and 2 are seen to go straight up and avoid collisions.
Balls 3 and 4 have one collision each before rushing upwards.
Balls 5 and 6 have 2 collisions before rushing upwards.
Balls 7 and 8 have 3 collisions before rushing upwards
Case I:
You have supplied a total of 64J of energy to the balls.
Let’s assume each ball gets 8 J of energy.
Ball 1 & 2 will rush directly upwards and come out. So 5J is wasted in coming out. So, balls 1 & 2 come out with 3J of energy each.
Clear till here.
Let’s talk about balls 3 & 4. They both receive 8J of energy. They collide once on their way and lose 2J each. So they are left with 6J each. Now in the process of coming out they will lose 5J each. So each of them comes out with 1J of energy.
Balls 5 & 6 will have 2 collisions each and lose 4J each, so will be left with (8 – 4 J) = 4J, which is not sufficient enough to cross over.
So only balls 1, 2, 3, 4 could cross over.
Now if you increase the total energy received by the group of balls from 64 J to 80 J, then each ball will receive 10J.
Balls 1, 2, 3, and 4 which were coming out with 8J only will still come out, right?
What about 5 & 6? They will have 2 collisions before rushing out. So will lose 4J each and will be left with 6J each, which is greater than 5J, so will come out with 1J each. Balls 7 & 8 will have 3 collisions, lose 6J each will be left with 4J each which is not sufficient to come out.
So we see that by increasing energy we increased the number of balls coming out.
similarly, all free electrons have equal probability of receiving energy but some come out directly by overcoming the work function(will have high kinetic energy) while others lost some extra energy in collisions and then come out after overcoming the work function (will have lower kinetic energy).
The rest of the electrons lose all their energy in collisions and don't have sufficient energy left to overcome the work function and don’t come out.
Now if you increase the intensity you have increased the energy received by each electron on an average. Earlier the electrons that were losing energy in collisions and didn't have enough energy left to overcome the work function, gain sufficient energy to do so now. Hence the number of electrons coming out has increased and thereby the current has increased too.
The number of electrons being ejected out has increased as electrons now receive higher energy and thus even after losing energy in collisions, have sufficient left to overcome the work function and come out.
Imagine there is a wall and there are 8 balls that you need to throw over to the other side.
Say, it’s given that the minimum energy required by a ball to cross over the wall is 5J, and in each collision a ball loses 2J of energy.
Let’s look at how some of the balls undergo collisions with the neighboring balls and lose energy, and record our observations as follows.
Balls 1 and 2 are seen to go straight up and avoid collisions.
Balls 3 and 4 have one collision each before rushing upwards.
Balls 5 and 6 have 2 collisions before rushing upwards.
Balls 7 and 8 have 3 collisions before rushing upwards
Case I:
You have supplied a total of 64J of energy to the balls.
Let’s assume each ball gets 8 J of energy.
Ball 1 & 2 will rush directly upwards and come out. So 5J is wasted in coming out. So, balls 1 & 2 come out with 3J of energy each.
Clear till here.
Let’s talk about balls 3 & 4. They both receive 8J of energy. They collide once on their way and lose 2J each. So they are left with 6J each. Now in the process of coming out they will lose 5J each. So each of them comes out with 1J of energy.
Balls 5 & 6 will have 2 collisions each and lose 4J each, so will be left with (8 – 4 J) = 4J, which is not sufficient enough to cross over.
So only balls 1, 2, 3, 4 could cross over.
Now if you increase the total energy received by the group of balls from 64 J to 80 J, then each ball will receive 10J.
Balls 1, 2, 3, and 4 which were coming out with 8J only will still come out, right?
What about 5 & 6? They will have 2 collisions before rushing out. So will lose 4J each and will be left with 6J each, which is greater than 5J, so will come out with 1J each. Balls 7 & 8 will have 3 collisions, lose 6J each will be left with 4J each which is not sufficient to come out.
So we see that by increasing energy we increased the number of balls coming out.
similarly, all free electrons have equal probability of receiving energy but some come out directly by overcoming the work function(will have high kinetic energy) while others lost some extra energy in collisions and then come out after overcoming the work function (will have lower kinetic energy).
The rest of the electrons lose all their energy in collisions and don't have sufficient energy left to overcome the work function and don’t come out.
Now if you increase the intensity you have increased the energy received by each electron on an average. Earlier the electrons that were losing energy in collisions and didn't have enough energy left to overcome the work function, gain sufficient energy to do so now. Hence the number of electrons coming out has increased and thereby the current has increased too.
