In parallax method for the determination of focal length of a concave mirror, the object should always be placed :
Answer key (B) & worked solution
Correct answer: Option B
Image should be real. So object should be placed beyond focus.
Updated 19 Oct 2026
In the real JEE Main computer-based test, clicking an option radio button and moving to another question does not save your answer: your choice counts only after you click SAVE & NEXT or SAVE & MARK FOR REVIEW. Try the playable 6-question NTA CBT demo below with real past-paper questions, then check your score immediately.
#E3E3E3): You have not opened this question yet.#E24401): You visited the question (or even clicked a radio button) and left without clicking SAVE & NEXT.#2FAF00): You selected an option and clicked SAVE & NEXT. It will be evaluated.#6B41AE): You clicked MARK FOR REVIEW & NEXT without saving an answer. It counts as unattempted (0 marks) if left as is.Correct answer: Option B
Correct answer: Option B
Correct answer: Option A
Correct answer: Option C
Correct answer: Option B
Correct answer: Option C