Which of the following types of radiation is negatively charged? A) Alpha radiation. B) Beta radiation. C) Gamma radiation. D) Free neutrons.
Okay, so to answer this question, let’s first recall what each one of these types of radiation actually is. First of all, we can start with alpha radiation. Now, alpha radiation, also known as a helium nucleus, is a particle which consists of two protons and two neutrons. And the reason it’s known as a helium nucleus is because the element with two protons in its nucleus is helium. And since an alpha particle doesn’t have any electrons orbiting the nucleus, we can therefore say that an alpha particle is the same thing as a helium nucleus.
So what’s the charge on an alpha particle? Well, we can see that an alpha particle consists of one, two protons. Protons are positively charged. We say that each one has a relative charge of plus one. And as well as this, the alpha particle is also made up of two neutrons. But neutrons are neutral particles. They don’t have any charge. And so we can say that they have a relative charge of zero.
Therefore, adding up all of these charges together, we see that the total charge on the helium nucleus or the alpha particle is positive one plus another one for the two protons. And then we add the charges of the two neutrons which are zero and zero, respectively. Altogether, that gives us a charge of positive two. Therefore, an alpha particle or alpha radiation in general is positively charged. Hence, it cannot be the answer to our question, since we’re looking for negatively charged radiation.
Let’s move on then to option B, beta radiation. Beta radiation simply is an electron. And we can recall that an electron has a charge of negative one. And it is worth noting by the way that whenever we say beta radiation without any qualification, we can often take it to mean 𝛽 minus radiation which, in fact, is an electron.
There is another type of beta radiation which is 𝛽 plus radiation which actually isn’t an electron but rather a positron which is the antiparticle of an electron and actually has a positive one charge. However, 𝛽 plus radiation does a lot less common than 𝛽 minus radiation. And so whenever we say beta radiation by itself without any qualification, we usually take it to mean 𝛽 minus. Therefore, option B looks like it could be the answer to our question.
Let’s quickly run through options C and D though to make sure that they are indeed incorrect answers. Firstly, option C, option C is gamma radiation. Now, gamma radiation is neither made up of protons and neutrons nor is it made up of electrons. In fact, gamma radiation is an electromagnetic wave. And as we can recall, electromagnetic waves do not have any charge. Therefore, option C is not the right answer to our question either.
Finally, option D is talking about free neutrons. These are neutrons that are not bounded by any nucleus. However, as we saw when we discussed alpha radiation, neutrons are neutral particles. They have zero charge. And hence, they cannot be negatively charged, regardless of whether they’re in a nucleus or whether they’re free. And hence, we found our final answer. Out of these four types of radiation, the type of radiation that is negatively charged is beta radiation.