Physics teachers fear their subject will suffer because good marks have been so hard to come by in the first year of the new National qualifications.
The concern - which some have applied to science subjects in general - is that physics will be perceived as more difficult and that uptake will suffer a long-term decline.
"Many physics teachers are expressing concern that pupils appear to be scoring lower grades than in other subjects, including maths," said Stuart Farmer, the coordinator for the Institute of Physics' Teacher Network.
"This has not generally been the case previously. It would be unfortunate if the demands of the new SQA [Scottish Qualifications Authority] assessment reinforces the outdated myth that physics is a hard subject, especially at a time when the number of pupils studying physics has been on the increase and the sorts of knowledge and skills it can provide are in high demand."
These concerns have been echoed on Sputnik, an online physics forum. One poster said that "assignment marking is all over the place", with the SQA "taking a nit-picking, box-ticking approach to marking that means good quality pieces of work are being given absurdly low marks".
Analysis by one teacher showed that 86 per cent of candidates would pass five or more subjects among a typical cohort taking National 5 English, maths, PE, drama, German and design and manufacture. If, however, the same cohort went through National 5 English, maths, physics, biology, geography and French, then only 55 per cent would reach the same level.
"There's nothing anecdotal about it - it is simply harder to pass N5 sciences than all other mainstream subjects, and it is harder to obtain a grade A," one commenter said.
"How long until kids, parents, headteachers and councils realise that the route to five good passes is to give science a miss and under no circumstances do two sciences?"
Nick Hood, a University of Edinburgh teaching fellow who runs the Scottish Physics Teaching Resources website, said that there had been "a bit of grumbling about the perceived unfairness of the new exams" on both physics and chemistry candidates. He added, however, that it might be no bad thing for physics to be seen as a difficult subject.
"Personally, I don't have a problem with this perception because it is hard," he said. "The problem that seems to have been identified - if it is true - is that the SQA seems to have abandoned the idea that all A grades are equal."
Mr Hood, who stressed that he was giving his personal opinions, queried what steps the SQA had taken to ensure that similar standards between subjects had been maintained, and what evidence existed to verify this.
He said he believed that independent analysis of SQA data would reveal that "parity does not exist between subjects and this it is a lot harder to get an A in physics than it is in almost any other subject".
An SQA spokesman said: "SQA takes its responsibility to uphold the high standards of Scottish qualifications very seriously. We have a very robust set of mechanisms in place to ensure that all our qualifications - including the new Nationals - offer an appropriate level of challenge for candidates."