Magnetic fields, induction, and light.
Sound, frequency, and wave propagation.
You can easily find digital versions of this specific "reshebnik" on massive Russian educational portals. Common platforms offering interactive table-of-contents by exercise number include: reshebnik po fiziki 9 klass peryshkin
Students use them to check their self-solved answers against the professional keys. Magnetic fields, induction, and light
Educators strongly advise against treating reshebniki as a simple "copy-paste" tool. To get actual academic value, students are encouraged to on their own and only use the reshebnik as a diagnostic reference point to find mathematical errors or formula misapplications. A. V. Peryshkin: Books - Amazon.com and light. Sound
