The photo cell works on the principle of the

Velapearl

2 months ago

The question says: The photo cell works on the principle of…
So the real thing we are looking for is not the word “photo cell” alone, but what actually happens inside it. A photocell is one of those devices that reacts to light. That is the biggest clue sitting inside the question.
Now, imagine a photocell like a small electronic “eye”. When light shines on it, something inside it responds. The key thing is that light has energy. And when that energy hits certain materials, it can knock out tiny particles called electrons.
That is the whole story. Light comes in, electrons come out.
Now let’s look at the options carefully, one after the other, and I’ll show you why only one of them makes sense.
Option A says “voltaic cell”. A voltaic cell is basically a battery. It produces electricity from chemical reactions. So instead of light doing anything, it is chemicals reacting that produce current. That is a completely different idea. No light knocking anything out. So this one is not related to what we are talking about.
Option C says “emission of protons by incident radiation”. This one already sounds suspicious if you slow down and think. Protons are inside the nucleus of an atom. They are not what normally gets knocked out by light in everyday physics situations like photocells. In fact, light does not just eject protons like that in this context. So this option is trying to sound scientific, but it is not describing what happens in a photocell.
Option D says “photographic plate”. This is related to cameras and film. A photographic plate reacts to light by forming an image chemically on a surface. That is about image formation, not generating current or releasing electrons for electricity. So again, it is in the “light-related” family, but not the principle behind how a photocell works.
Now we reach Option B, and this is where everything clicks.
It says “emission of electrons by incident radiation”.
Let’s break that phrase into normal language. “Emission” simply means release or giving out. “Electrons” are tiny charged particles inside atoms. “Incident radiation” is just a fancy way of saying incoming energy, usually light.
So if we translate it properly, it is saying: when light shines on a material, electrons are released.
Now connect that back to what I told you earlier. A photocell works when light hits a surface and knocks out electrons. Those electrons then create an electric current. That is literally the working principle.
So Option B is not just correct, it is exactly describing what is happening inside the device.
If you want a very simple mental picture that you can carry into the exam, think of it like this. Light hits a surface, and the surface “spits out” electrons. Those electrons are then collected and turned into electricity. That is a photocell.
So the answer is B.