You’ve got less than a week till you have to sit your HKDSE Physics exam. To make sure you don’t lose marks from misinterpreting the questions or making careless mistakes, Young Post speaks to star Physics tutors, CY Chau from King’s Glory Education Centre and Wayne Leung from Beacon College, for advice on how to snag as many points as you can.
Topics and past papers
Chau advised students to familiarise themselves with the topics Heat and Wave, as the questions set on these questions are usually more simple and straightforward. Students should also make sure they understand how a transmission electron microscope works, says Leung. “There is a fair chance that will be tested in one of the long questions in Paper 2.”
Chau also said it might be worthwhile for student to go through past Hong Kong Advanced Level Examination papers, in addition to doing past DSE papers, as many questions in last year’s exam were similar to those found in the HKALE.
Students who’ve looked at past HKALE papers will find these “repackaged” questions easy to handle, Chau says, whereas those who did not might find them unfamiliar and challenging.
Chau also pointed out that there were more questions in last year’s paper, which required students to do some problem solving and come up with solutions to experimental errors.
This cost a lot of students points in the exam, as many of them were not used to these sorts of questions. Dealing with experimental errors, however, was a part of the HKALE syllabus.
One common mistake is that students confuse the word “describe” with the word “explain”, which can lose them a lot of points. “It is a waste of time to give explanations [when asked to describe something], because you will get no marks for doing it,” says Chau.
Moreover, students should remember that when giving their opinion, they should give evidence to back up what they are saying. “Science should be objective. Students should always support their answers with equations, laws, or theories they’ve learned,” Chau adds.
When students tackle the experiment-themed question which asks them to describe an experiment or apparatus used, they often waste time explaining scientific concepts related to the experiment which will not gain them extra points. “What they should actually do is write down the experimental procedure step by step,” says Leung.
Students also need to pay extra attention when they are asked to draw ray diagrams, he adds. “Marking schemes have suggested that students often mix up the use of solid lines with dotted lines,” says Leung. “They should bear in mind that solid lines are only used for depicting real image and light rays, while dashed lines are for virtual images and imaginary light rays.”
Students should also remember to use arrows to show the direction of light beams between an object and an eye or lens, says Leung. Another common mistake occurs when students are asked to recommend methods to bring about a certain physical change in an experiment.
Leung says students often suggest how a depending factor should be changed, when they should instead list the actions needed to be carried out to bring about these changes.
Grab all the marks you can get
If you encounter a question that you’re not sure how to answer, don’t start making things up, says Chau. For example, there might be a question that requires you to explain each phase of a physical phenomenon, but you may not know all the phases involved.
You can still gain points by mentioning the phases you do know. If you’re stuck, try working your way backwards and use every bit of information given to make reasonable deductions.
Chau said it doesn’t matter if you are not able to identify the initial factor which drives the process of physical change to take place, said Chau. “You will still get marks for giving logical explanations for part of the process.”
Students should never make blind guesses when they can’t figure out the answer in a multiple choice question, said Leung. “They should take 10 minutes to scan the question, and eliminate the answers that are obviously wrong,” he says.
For example, if the question is about finding the refractive index, students can eliminate answers whose value is smaller than one, which is the minimum refractive index of all matters. “That way, you can increase the probability of making the right guess for a question that you cannot answer.”