Video Transcript
The truth table shows the output of
an AND gate for various combinations of inputs. What is the value of 𝑝 in the
table? What is the value of 𝑞 in the
table? Okay, so in this question, we’ve
been given a truth table for an AND gate specifically. But instead of it being completely
filled with zeros and ones, we see that in this location we’ve got the letter
𝑝. And in this location, we’ve got the
letter 𝑞. Now the question is asking us to
work out the values of 𝑝 and 𝑞. So to do this, we need to remember
what the behaviour of an AND gate is. We can recall that the AND gate
gives an output of one only if input A and input B are set to one. In other words, in any other
combination of input such as zero, zero or zero, one or one, zero, the output is
still going to be zero. However, if both inputs are set to
one, then the output is going to be set to one as well.
So let’s start by looking at letter
𝑝. We can see that letter 𝑝
represents the output of an AND gate in the situation where input A is set to zero
and input B is set to one. Well, in this case, both of the
inputs aren’t set to one, only one of them is. And so the AND gate will give an
output of zero. And hence, we can say that the
value of 𝑝 in the table is zero. So let’s move on to looking at
letter 𝑞. Now 𝑞 represents the output when
input A is set to one and input B is set to one. And as we can see from the
statement here, when both inputs are set to one, then the output of the AND gate
will also be set to one. And hence, we can say that the
value of 𝑞 in the table is one.