Provided the resolution (bandwidth) is narrow enough to differentiate between the frequencies and the waveform is a sine wave, you would see a single spike in the trace that jumped from side to side as the frequency changed. If it isn't a pure sine wave, in other words it is composed of a fundamental plus some other frequencies, you would see the main spike jump from side to side with some smaller spikes around it, each representing the other frequencies or mixing products.
Depending on how fast 'T' actually is in respect of the sweep rate, the jump from side to side may visually appear as two spikes at once even though only one is really present at a time.
Brian.