SnekiSnek
Unlike other subjects, for physics, you really need to understand the material rather than doing a tedious amount of practice questions. Physics questions tend to test you on your understanding so it's really important you understand the material rather than doing the practice questions! Physics is not a subject like maths where you get better over a lot of practice, rather you get better by understanding the material better (and having the VCE Formula sheet on you).
I would definitely go back to basics with your fundamental understanding of light as a wave, and before you start trying more practice questions, watch a few demos on light experiments and how they can be analysed graphically. When it comes to answering physics questions, really think about what it's asking you and think about how you may get there. There are many ways to answer physics questions so that's why it's important to understand the topic inside out before continuing!
Hope that helps 😄
