Why Is Focal Length Negative in Concave Mirror? | Sign Convention Explained | Class 10 Science

Why is the focal length of a concave mirror taken as negative? In this video, we explain sign convention in spherical mirrors and the reason behind negative focal length of concave mirror in a simple, exam-oriented way. This concept is very important for CBSE Class 10 board exams 2026 and numericals from Light – Reflection and Refraction chapter. 🔹 Topics covered in this video: • Sign convention for mirrors (New Cartesian Sign Convention) • Position of focus in concave mirror • Why focal length becomes negative • Ray diagram based explanation • Common mistakes students make 📌 Watch till the end for exam tips & numerical clarity. 🔔 Subscribe to Science World by Tushar Sir for Class 10 Science concepts explained clearly. ................................................................................................... For Simplified Notes, NCERT Solution and Important Question you can visit our website: • For Notes: https://www.scienceworldbytusharsir.in/ • For our Courses: https://www.scienceworldbytusharsir.com/ • For Science Fundamental: https://www.thescienceworld.in/ You can download our app from play store Here we arrange different courses for class 9th to 12th in which you will get important questions, notes, videos and assignments. • For Mobile app: https://clprios.page.link/wVCY .................................................................................................. Related query: why focal length is negative concave mirror focal length why focal length of concave mirror is negative sign convention class 10 light reflection and refraction class 10 concave mirror sign convention class 10 physics light cbse class 10 science 2026 focal length sign convention mirror formula class 10 science world by tushar sir